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Mar 19, 2018 - Department of Chemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, Hong Kong. SAR. §. Depa...
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Cite This: J. Org. Chem. 2018, 83, 3433−3440

Biconcave and Convex−Concave Tribenzotriquinacene Dimers Zhi-Min Li,† Ya-Wei Li,† Xiao-Ping Cao,*,† Hak-Fun Chow,*,‡ and Dietmar Kuck*,§ †

State Key Laboratory of Applied Organic Chemistry and College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, P.R. China ‡ Department of Chemistry and Center of Novel Functional Molecules, The Chinese University of Hong Kong, Shatin, Hong Kong SAR § Department of Chemistry and Center for Molecular Materials (CM2), Bielefeld University, 33615 Bielefeld, Germany S Supporting Information *

ABSTRACT: A new chiral tribenzotriquinacene bearing an ortho-bromoaniline nucleus was synthesized and optically resolved. The individual enantiomers, the absolute configuration of which was confirmed by single-crystal X-ray structure analysis, were stereoselectively converted into the same pyrazine-fused syn-bis-TBTQ derivative by chiralityassisted Buchwald−Hartwig amination. The corresponding diastereomeric anti-dimer was obtained alongside the syndimer from the racemic sample under similar reaction conditions. X-ray structure analysis of the dimers confirmed the mutual biconcave and convex−concave configuration of their TBTQ moieties and the preservation of the orthogonal orientation of the indane wings within each of them.

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INTRODUCTION Nonplanar, polycyclic molecules such as cyclodextrins, corannulenes, sumanenes, and subphthalocyanines have created immense interest among scientists in the field of supramolecular chemistry.1 The bowl-shaped polycyclic framework of tribenzotriquinacene, TBTQ (1, Figure 1a),2 bearing three rigidly fused indane wings oriented orthogonally in the threedimensional space has been explored for many years with regard to its applicability in host−guest chemistry and supramolecular chemistry3−8 and for the construction of warped nanographenes.9 Due to its unique geometry, the TBTQ motif has been envisioned and used as a building block for the assembly of covalent molecular cubes5 and hydrogenbonded cubic capsules containing eight TBTQ units (2, Figure 1b).6 Other assemblies containing two or more TBTQ units, such as cryptands,7 deeply concave tetrameric hosts,8 a bisTBTQ metallocryptophane, 4 and a molecular (TBTQ) 4 square10 have already been reported. However, systematic approaches to dimeric and oligomeric elements of rigid (TBTQ)8 cubes, which would enable selective encapsulation of guest molecules and be more stable toward environmental changes of pH value and solvent polarity as compared to hydrogen-bonded cubic capsules,11 remain scarce to date. Recently, two bis-tribenzotriquinacenes, syn-312 and syn-4,13 were reported along with their anti-isomers (Figure 1c). The anti-isomers were formed as the major isomers (e.g., anti-3/syn3 ≈ 3:1), and the crystal structure of anti-4 was determined. Therefore, the stereocontrolled synthesis of TBTQ syn-dimers such as 3 and 4 that represent a properly oriented edge of the © 2018 American Chemical Society

corresponding (TBTQ)8 cubes still remains unachieved and is a major challenge on the way to a new family of rigid, covalently bonded TBTQ-based oligomers. Employing enantiomerically pure building blocks, the socalled chirality-assisted synthesis (CAS)14 was demonstrated and emphasized15 to be an efficient strategy to enforce the formation of covalently bound syn-biconcave molecular architectures and to exclude that of the corresponding undesired anti-diastereomers. Several enantiomerically pure C3-symmetrically functionalized TBTQ derivatives are known, and some of them were shown to undergo noncovalent assembling in the solid state or in solution.5a,6 Other enantiomerically pure TBTQ derivatives bearing only one or two functionalized indane wings were also synthesized using different methodologies.12,16 In the present work, we have focused on the synthesis of a new single-wing difunctionalized TBTQ building block, the 2-amino-3-bromo-TBTQ derivative 5, and its optical resolution. We also report that the pure enantiomers (M)-5 and (P)-5 could be used to efficiently construct the desired pyrazine-fused bis-TBTQ derivative syn-6 as the edge of the corresponding, yet hypothetical, (TBTQ)8 cube employing the CAS strategy (Figure 1d).

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RESULTS AND DISCUSSION Whereas three- and six-fold peripheral nitration of the TBTQ framework and subsequent reduction to the corresponding Received: February 8, 2018 Published: March 19, 2018 3433

DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440

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diastereomers obtained from condensation of (S)-2,2′dihydroxy-1,1′-dinaphthalene-3-carbaldehyde, (S)-10,18 and TBTQ-bromoaniline (±)-5 could be readily separated by column chromatography [see Supporting Information (SI)]. Hence, optically pure (−)-(M,S)-11 ([α]D25 −372, c 0.5, CH2Cl2) and (+)-(P,S)-11 ([α]D25 +318.0, c 0.5, CH2Cl2) were obtained in 41 and 44% yield, respectively (Scheme 2). Their Scheme 2. Resolution of 2-Amino-3-bromo-TBTQ (±)-5 Employing (S)-2,2′-Dihydroxy-1,1′-dinaphthalene-3carbaldehyde, (S)-10

Figure 1. (a) Parent tribenzotriquinacene (1) bearing three orthogonally oriented indane wings. (b) Hypothetical (TBTQ)8 cube 2 with one of its (TBTQ)2 edges highlighted. (c) Known TBTQ dimers 3 and 4 (syn-isomers). (d) Construction of the pyrazine-fused (TBTQ)2 “edge” syn-6 from the enantiomerically pure 2-amino-3-bromo-TBTQ (M)-5 and (P)-5 by chirality-assisted cycloamination.

amines has been reported,5a,17 single-wing functionalized 2nitro- and 2-aminotribenzotriquinacenes are unknown to date. In the present work, hydrocarbon 7 was reacted with potassium nitrate (1.0 equiv) in a mixture of trifluoroacetic acid (TFA) and dichloromethane (CH2Cl2) at ambient temperature for 5 h to give the 2-nitro derivative (±)-8 in excellent efficiency and on the gram scale (Scheme 1). The crude product was then

structures were confirmed by 1H and 13C NMR spectroscopy (Figure 2 and SI, Figures S5−S8) and by mass spectrometry. Slight but significant differences in the chemical shift values of the corresponding proton signals were observed in the 1H NMR spectra. For example, the NCH protons of (−)-(M,S)11 and (+)-(P,S)-11 resonate at δ 9.25 and δ 9.23, respectively, and part of the ortho-protons at the naphthalene rings appear at slightly different chemical shifts (Δδ = 10−30 ppb, Figure 2). Moreover, the chemical shifts and splitting of the arene protons of the nonfunctionalized TBTQ wings rings differed in the range of δ 7.65−7.00. Similar differences in the 13C NMR spectral data of the diastereomers (−)-(M,S)-11 and (+)-(P,S)11 were also noted (SI, Figure S8). Accurate mass measurements by ESI-TOF mass spectrometry corroborated the identity of (−)-(M,S)-11 and (+)-(P,S)-11 (SI, Figures S19 and S20). The enantiomerically pure TBTQ-based bromoanilines (−)-(M)-5 ([α]D25 −4.0, c 0.5, CH2Cl2) and (+)-(P)-5 ([α]D25 +4.0, c 0.5, CH2Cl2) were then obtained in good yields (87 and 89%) by hydrolysis of (−)-(M,S)-11 and (+)-(P,S)-11, respectively, with aqueous hydrochloric acid (6 M) in acetone for ∼2 days. The purity of the enantiomers was 96% for (−)-(M)-5 and >99.9% ee for (+)-(P)-5, as determined by chiral HPLC analysis (SI, Figure S1). Experimental ECD spectroscopy of the pure enantiomers, (−)-(M)-5 and (+)-(P)-5, revealed almost perfect mirror images, reflecting their high optical purity (Figure 3). Single crystals of both (−)-(M)-5 and (+)-(P)-5 were grown from CH2Cl2/MeOH = 5/1 and from CH2Cl2 solution, respectively, and X-ray diffraction crystallography confirmed the absolute configuration of the two enantiomers. The refined Flack

Scheme 1. Synthesis of the Racemic 2-Amino-3-bromoTBTQ Derivative 5

subjected to reduction with sodium borohydride in methanol in the presence of NiCl2·6H2O to afford the 2-amino-TBTQ derivative (±)-9 in 93% overall yield from 7. Subsequent bromination of compound (±)-9 with N-bromosuccinimide (NBS) in acetonitrile at 60 °C furnished the disubstituted TBTQ-based ortho-bromoaniline (±)-5 in almost quantitative yield (98%). In the next step, optical resolution of racemate (±)-5 was required. After many attempts, it was found that the imine 3434

DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440

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Figure 2. Partial 1H NMR spectra (600 MHz, acetone-d6) of (−)-(M,S)-11 (top) and (+)-(P,S)-11 (bottom). The marked pairs of signals are commented in the text.

With the enantiomerically pure TBTQ building blocks (−)-(M)-5 and (+)-(P)-5 in hand, the Pd-catalyzed two-fold C−N cross-coupling reactions with each of the enantiomers were carried out (Scheme 3).14,20 Use of palladium acetate and Scheme 3. Synthesis of the Pyrazine-Fused Dimer syn-6 from the Enantiomerically Pure (−)-(M)-5 and (+)-(P)-5

Figure 3. Experimental ECD spectrum of the pure enantiomers (−)-(M)-5 (red) and (+)-(P)-5 (blue) (CH2Cl2, c = 3.89 × 10−4 mol/ L).

dicyclohexyl-(2′,6′-diisopropoxy-[1,1′-biphenyl]-2-yl)phosphine (RuPhos) as a ligand in the presence of cesium carbonate furnished the pyrazine-fused condensation product syn-6 with the syn-biconcave molecular topography in good yield (60 and 62%). Thus, with concomitant dehydrogenation, each of the two enantiomers led to the same achiral cyclocondensation product. Use of dicyclohexyl-(2′,6′-dimethoxy-[1,1′-biphenyl]-2-yl)phosphine (SPhos) under otherwise the same reaction conditions gave significantly lower yields of syn-6. The 1H and 13C NMR spectra of syn-6 clearly reflected the molecular symmetry (C2v in the case of this isomer; see below). The 1H NMR spectrum showed only four groups of arene resonances (Figure 5 and SI, Figure S11). Among these, the singlet at δ 8.09 indicated the four isolated protons at the phenazine unit. The remaining arene multiplets exhibit the characteristic splitting of the resonances of the inner and outer protons at the TBTQ peripheries. Moreover, the signals of the inner methylene groups at δ 2.1−2.4 were split into two separated groups, in line with the molecular symmetry of syn-6. The 13C NMR spectrum of syn-6 also confirmed its structural identity; for example, only eight (of the expected nine) arene carbon resonances were observed, again in accordance with the increased molecular symmetry (SI, Figure S11). Furthermore, X-ray diffraction analysis of single crystals of syn-6 grown from

parameters, 0.002(8) and 0.012(7) for (−)-(M)-5 and (+)-(P)5, respectively, were very close to zero, indicating that the correct configuration had been assigned.19 The solid-state molecular structures of the TBTQ-based ortho-bromoanilines (−)-(M)-5 and (+)-(P)-5 are depicted in Figure 4 (see also SI, Figures S13 and S14 for further details).

Figure 4. Solid-state molecular structures of the 2-amino-3-bromoTBTQ enantiomers (−)-5 (left) and (+)-5 (right) with thermal ellipsoids drawn at 30% probability, as determined single-crystal X-ray diffraction analysis. 3435

DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440

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Scheme 4. Synthesis of the Mixture of the Pyrazine-Fused Dimers anti-6 and syn-6 from the Racemate (±)-5

isomer, anti-6, whereas the more polar one (Rf = 0.44) was confirmed to be the syn-isomer, syn-6, by comparison with an authentic sample obtained by the CAS strategy. It is worth noting that the 1H and 13C NMR spectra of anti-6 and syn-6 exhibited only very minor differences in the chemical shifts, which rendered an independent assignment of the stereochemistry impossible. For illustration, the partial 1H NMR spectrum of anti-6 is contrasted to that of syn-6 in Figure 5 (see also SI, Figures S11 and S12). The singlet for the four isolated protons at the phenazine unit of anti-6 appeared at δ 8.08, as compared to δ 8.09 for the syn-isomer, and the Δδ values of other protons were also minute. The resonances of the peripheral arene protons of anti-6 were slightly shifted to lower field as compared to those of syn-6. Single crystals of diastereomer anti-6 suitable for X-ray diffraction analysis were obtained from a chloroform solution by slow evaporation.19a The molecular packing in the crystals of anti-6 was found to be much more complicated than that of the syn-6 diastereomer (Figure 6; see also SI, Figures S15 and S16 for details). The phenazine core of anti-6 is perfectly planar with C2h-symmetrical conformation, but for syn-6, the cyclocondensation gives rise to a slight distortion of the phenazine core and even of the three indane units in each TBTQ moiety. Here, the dihedral angle between the planes of the two inner benzene rings is about 3.5°. In the crystals of diastereomer syn6, two neighboring molecules are packed with one molecule facing up and the other facing down. The neighboring molecules are cross-stacked with the planes of the phenazine units being parallel to each other. CH···π interactions occur between the terminal methyl groups and the pyrazine unit of the adjacent molecule. The length and depth of the molecular strips of syn-6 were found to be 11.84 and 3.69 Å, respectively. The three axes comprising the central carbon and the centers of the outer peripheral indane C−C bonds cross each other at the central carbon atom at angles in the range of 81.6−89.0°. In the crystals of diastereomer anti-6, the molecules are stacked more regularly than in those of syn-6. However, the asymmetric unit of anti-6 contains two molecules with different conformations and four solvent molecules. CH···π interactions are found between the chloroform molecule and the peripheral benzene rings. The lengths and depths of the molecular strips of anti-6 are 11.84 (11.91) and 3.88 (3.88) Å, respectively. The three axes comprising the central carbon atom and the centers of the outer peripheral indane C−C bonds cross at the central carbon at the angles of 82.7−85.6° (83.2−88.7°). We believe that the deviation from the almost orthogonal geometry found in the

Figure 5. Stacked partial 1H NMR spectra (400 MHz, CDCl3) of the diastereomeric pyrazine-fused bis-TBTQ derivatives anti-6 (top) and syn-6 (bottom).

a mixture of CH2Cl2/MeOH = 20/1 was performed and revealed details of the extended syn-bis-TBTQ framework, as discussed below (Figure 6 and SI, Figure S15).19a

Figure 6. Solid-state molecular structures of the diastereomeric pyrazine-fused bis-TBTQ derivatives syn-6 (top) and anti-6 (bottom) with thermal ellipsoids drawn at 30% probability, as determined by single-crystal X-ray diffraction analysis.

The cross-coupling reaction discussed above was also carried out with the racemic starting material (±)-5 under the same reaction conditions used for the pure enantiomers (Scheme 4). As expected, a mixture of both of the diastereomeric condensation products, anti-6 and syn-6, was formed in this case in similar total amount. Careful column chromatography (petroleum ether/EtOAc = 100/1) allowed us to separate the two diastereomers. The less polar fraction (TLC: Rf = 0.46, petroleum ether/EtOAc = 5/1) turned out to be the anti3436

DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440

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(multiplet). Melting points were determined by use of a microscope apparatus and are uncorrected. High-resolution mass spectra were obtained on a Thermo Fisher Scientific LTQ-Orbitrap-EDT instrument using electrospray ionization (ESI) technique. Analytical chiral high-performance liquid chromatography (HPLC) was conducted on a Waters 1525/2998 instrument. UV−vis spectra were measured on a Cary 300 spectrophotometer. Circular dichroism spectra were measured on a JASCO J-810 spectropolarimeter. Single-crystal X-ray structural analyses of compounds (−)-(M)-5 and 6 were performed on a SuperNova detector, and the analysis of compound (+)-(P)-5 was performed on a Bruker APEX-II CCD detector, using Mo Kα radiation in all cases. Fluorescence emission spectra were measured on a Shimadzu RF5301 fluorescence spectrophotometer. Compound 7 was synthesized as reported previously.16b (±)-12d-Methyl-2-nitro-4b,8b,12b-tripropyl-4b,8b,12b,12dtetrahydrodibenzo[2,3:4,5]pentaleno[1,6-ab]indene [(±)-8]. Trifluoroacetic acid (5 mL) was added to a stirred solution of tribenzotriquinacene 7 (1.50 g, 3.57 mmol) in dichloromethane (100 mL) at 0 °C, then KNO3 (361 mg, 3.57 mmol) was added in three portions over a period of 3 h. The reaction mixture was then stirred at room temperature for an additional 2 h. The mixture was quenched by addition of cold water (10 mL) and then basified to pH 8−9 with 1 M NaOH solution. The aqueous layer was extracted with ethyl acetate (3 × 10 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated under reduced pressure to give the crude 2-nitrotribenzotriquinacene (±)-8 as a pale-yellow solid. This compound was used in the next step without further purification. Flash column chromatography (petroleum ether/EtOAc = 100/1) on silica using a small portion of the crude (±)-8 furnished analytically pure nitro-TBTQ (±)-8 as a colorless solid: mp 186−188 °C; Rf 0.8 (petroleum ether/EtOAc = 10/1); 1H NMR (400 MHz, CDCl3, 25 °C) δ = 8.18 (d, J = 2.0 Hz, 1H), 8.04 (dd, J = 8.4 and 2.0 Hz, 1H), 7.46 (dd, J = 8.4 and 2.0 Hz, 1H), 7.40−7.30 (m, 4H), 7.20−7.18 (m, 4H), 2.24−2.19 (m, 6H), 1.69 (s, 3H), 1.24−1.21 (m, 6H), 1.00−0.95 (m, 9H); 13C NMR (100 MHz, CDCl3, 25 °C) δ = 155.5 (C), 150.0 (C), 148.0 (C), 147.9 (C), 147.8 (C), 146.7 (C), 146.5 (C), 127.82 (CH), 127.77 (CH), 127.7 (CH), 127.5 (CH), 124.1 (CH), 123.6 (CH), 123.5 (CH), 123.1 (CH), 122.8 (CH), 118.9 (CH), 72.3 (C), 67.6 (C), 67.3 (C), 66.9 (C), 40.9 (CH2), 40.6 (CH2), 40.4 (CH2), 20.41 (CH2), 20.38 (CH2), 15.10 (CH3), 15.05 (CH3), 15.03 (CH3), 15.01 (CH3); one aromatic CH and one CH2 signals were not recognized due to overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C32H36NO2 466.2741; found 466.2742. (±)-12d-Methyl-4b,8b,12b-tripropyl-4b,8b,12b,12d-tetrahydrodibenzo-[2,3:4,5]pentaleno[1,6-ab]inden-2-amine [(±)-9]. Sodium borohydride (162 mg, 4.28 mmol) and NiCl2·6 H2O (10 mg, 40 μmol) were slowly added to a stirred solution of the crude compound (±)-8 (1.65 g) in MeOH (50 mL) at 0 °C. The mixture was stirred at room temperature for 3 h, and the reaction was monitored by TLC. It was quenched by addition of cold water (2 mL), and the solvent was removed under reduced pressure. The resulting residue was dissolved in water/ethyl acetate (1/1, 20 mL), and the aqueous layer was extracted with ethyl acetate (3 × 10 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered, and concentrated under reduced pressure. Flash column chromatography of the residue through basic alumina (petroleum ether/EtOAc = 50/1) produced 2aminotribenzotriquinacene (±)-9 (1.45 g, 93% for two steps from compound 7) as a colorless solid: mp 216 °C (decomp.); Rf 0.3 (petroleum ether/EtOAc = 4/1); 1H NMR (400 MHz, CDCl3, 25 °C) δ = 7.30−7.22 (m, 4H), 7.13−7.09 (m, 4H), 7.04 (d, J = 8.0 Hz, 1H), 6.59 (d, J = 2.0 Hz, 1H), 6.48 (dd, J = 8.2 and 2.2 Hz, 1H), 3.50 (br s, 2H), 2.16−2.08 (m, 6H), 1.59 (s, 3H), 1.24−1.15 (m, 6H), 0.91 (t, J = 7.2 Hz, 9H); 13C NMR (100 MHz, CDCl3, 25 °C) δ = 149.1 (C), 148.7 (C), 148.3 (C), 148.0 (C), 147.9 (C), 145.6 (C), 138.9 (C), 127.1 (CH), 127.02 (CH), 126.94 (CH), 126.8 (CH), 123.8 (CH), 123.30 (CH), 123.26 (CH), 123.2 (CH), 115.3 (CH), 109.5 (CH), 72.0 (C), 67.1 (C), 66.5 (C), 40.9 (CH2), 40.8 (CH2), 20.5 (CH2), 20.4 (CH2), 15.2 (CH3), 15.1 (CH3), one aromatic CH, one aliphatic C, two CH2, and two CH3 signals were not recognized due to

case of syn-6 is due to intermolecular packing of the molecules and that the overall rigidity of the pyrazine junctions merged with the TBTQ bowls will be an advantageous factor for the shape persistence of higher oligomers, such as the corresponding (TBTQ)8 cube. The absorption and emission spectra of anti-6 and syn-6 as well as of phenazine were also studied (SI, Figures S18 and S19). The UV−vis absorption spectra of anti-6 and syn-6 were very similar but differed strongly from phenazine and the starting material (±)-5 (SI, Figure S17). Compounds anti-6 and syn-6 exhibited red-shifted emission bands to 265 and 398 nm as compared to phenazine (250, 365 nm), reflecting the bathochromic shift due to the merging with the TBTQ moieties. To evaluate the electronic structures of anti-6 and syn6, we conducted density functional theory calculations at the B3LYP/6-31+G(d,p) level of theory in the Gaussian 09 suite of programs (SI, Figure S22). The HOMO−LUMO gaps were calculated to be 3.340 eV for anti-6 and 3.386 eV for syn-6. The close similarity of the electronic structure of the diastereomers is in accordance with the almost identical UV−vis absorption. The fluorescence of anti-6 and syn-6 was very weak, and only minor differences were observed when compared with phenazine in diluted solution. This may be ascribed to the lack of conjugation between the three aromatic wings of the TBTQ-based anti-6 and syn-6.21

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CONCLUSIONS In summary, an efficient synthesis of single-wing functionalized 2-aminotribenzotriquinacenes has been reported. These compounds represent promising intermediates as chiral bowlshaped building blocks for the construction of large covalently linked capsules in supramolecular chemistry. In particular, we have explored the synthesis of the 2-amino-3-bromo-TBTQ derivative (±)-5 and its optical resolution into the enantiomers (−)-(M)-5 and (+)-(P)-5 using, for the first time, (S)-2,2′dihydroxy-1,1′-dinaphthalene-3-carbaldehyde, (S)-10, as an efficient auxiliary. Two-fold Buchwald−Hartwig reaction of the pure enantiomers afforded the first chirality-assisted synthesis of a pyrazine-fused syn-bis-TBTQ derivative, which represents an edge of a hypothetical covalent cube that would consist of eight rigidly syn-fused TBTQ units. The synthesis and optical resolution of suitably functionalized chiral TBTQ derivatives that could lead to such novel deeply concave polyaromatic structures that may be of interest for applications in chiral recognition, asymmetric catalysis, and supramolecular chemistry are ongoing in our laboratories.

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EXPERIMENTAL SECTION

General Information. All reactions that required anhydrous conditions were carried out by standard procedures under argon atmosphere. Commercially available reagents were used without further purification. The solvents were dried by distillation over appropriate drying reagents. The petroleum ether (PE) used had a boiling range of 60−90 °C. Reactions were monitored by thin-layer chromatography (TLC) on silica gel GF 254 plates. Column chromatography was performed through silica gel (200−300 mesh). 1 H, 13C NMR, and DEPT 135 spectra were recorded on a 400 MHz Bruker Avance instrument (1H, 400 MHz; 13C, 100 MHz) or a 600 MHz Varian Inova instrument (1H, 600 MHz; 13C, 150 MHz). Chemical shift values (δ) are given in parts per million and coupling constants (J) in hertz (Hz). Residual solvent signals in the 1H and 13C NMR spectra were used as an internal reference (CDCl3: δ H 7.26, δ C 77.0 ppm; acetone-d6: δ H 2.05, δ C 206.26, 29.84 ppm). Multiplicity was indicated as follows: s (singlet), d (doublet), m 3437

DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440

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Bright-yellow solid; mp 179−180 °C; [α]D25 +318.0 (c 0.5, CH2Cl2); 1H NMR (600 MHz, acetone-d6, 25 °C, the signal of the non-hydrogen bonded phenolic H may merge with the residual water signal located at δ = 2.93) δ = 12.81 (br s, 1H), 9.23 (s, 1H), 8.35 (s, 1H), 8.01−7.99 (m, 1H), 7.91 (d, J = 9.0 Hz, 1H), 7.88 (d, J = 7.8 Hz, 1H), 7.83 (s, 1H), 7.81 (s, 1H), 7.64−7.63 (m, 1H), 7.54−7.53 (m, 1H), 7.49−7.47 (m, 2H), 7.36 (d, J = 8.4 Hz, 1H), 7.34−7.33 (m, 2H), 7.27 (ddd, J = 8.4, 7.2, and 1.2 Hz, 1H), 7.22−7.11 (m, 7H), 2.33−2.23 (m, 6H), 1.71 (s, 3H), 1.29−1.20 (m, 6H), 0.96−0.92 (m, 9H); 13C NMR (150 MHz, acetone-d6, 25 °C) δ = 164.7 (CH), 156.4 (C), 153.9 (C), 150.5 (C), 150.4 (C), 149.19 (C), 149.18 (C), 148.3 (C), 148.2 (C), 146.5 (C), 137.2 (C), 136.6 (CH), 135.3 (C), 130.2 (CH), 130.0 (CH), 129.9 (C), 129.6 (CH), 128.9 (CH), 128.8 (C), 128.7 (CH), 128.31 (CH), 128.28 (CH), 126.9 (CH), 125.6 (CH), 125.5 (CH), 124.53 (CH), 124.51 (CH), 124.5 (CH), 124.42 (CH), 124.37 (CH), 123.5 (CH), 122.5 (C), 119.9 (C), 119.5 (CH), 117.2 (C), 115.9 (C), 115.3 (CH), 73.0 (C), 68.4 (C), 68.2 (C), 68.0 (C), 41.4 (CH2), 41.2 (CH2), 41.1 (CH2), 21.28 (CH2), 21.25 (CH2), 21.22 (CH2), 15.7 (CH3), 15.29 (CH3), 15.27 (CH3), 15.2 (CH3), two aromatic CH signals were not recognized due to overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C53H4979BrNO2 810.2941, found 810.2930. (−)-(M)-3-Bromo-12d-methyl-4b,8b,12b-tripropyl-4b,8b,12b,12dtetrahydrodibenzo[2,3:4,5]pentaleno[1,6-ab]inden-2-amine [(−)-(M)-5]. Aqueous hydrochloric acid solution (HCl, 6 M, 2 mL) was added to a stirred solution of the diastereomer (−)-(M,S)-11 (259 mg, 0.32 mmol) in acetone (10 mL). The mixture was stirred for 46 h, and the reaction was monitored by TLC. After completion of the reaction, the acetone was removed under reduced pressure. The pH of the resulting aqueous layer was adjusted to 8−9 with 1 M aqueous NaOH and then extracted with ethyl acetate (30 mL). The organic layers were washed three times with 1 M NaOH and then with brine, dried over Na2SO4, filtered, and concentrated under reduced pressure. Flash column chromatography (petroleum ether/EtOAc = 50/1) of the residue through silica gel afforded ortho-bromo-TBTQ-amine (−)-(M)-5 (143 mg, 87%) as a colorless solid: mp 225−227 °C; Rf 0.5 (petroleum ether/EtOAc = 4/1); [α]D25 −4.0 (c 0.5, CH2Cl2); 1H NMR (400 MHz, CDCl3, 25 °C) δ = 7.30−7.28 (m, 2H), 7.27 (s, 1H), 7.24−7.20 (m, 2H), 7.14−7.11 (m, 4H), 6.65 (s, 1H), 3.74 (br s, 2H), 2.14−2.05 (m, 6H), 1.57 (s, 3H), 1.22−1.12 (m, 6H), 0.93−0.90 (m, 9H); 13C NMR (100 MHz, CDCl3, 25 °C) δ = 148.7 (C), 148.2 (C), 148.0 (C), 147.8 (C), 147.6 (C), 142.8 (C), 140.4 (C), 127.29 (CH), 127.26 (CH), 127.1 (CH), 126.9 (CH), 123.4 (CH), 123.3 (CH), 123.1 (CH), 110.1 (CH), 109.3 (C), 72.1 (C), 67.2 (C), 66.9 (C), 66.5 (C), 40.93 (CH2), 40.86 (CH2), 40.6 (CH2), 20.4 (CH2), 20.3 (CH2), 15.2 (CH3), 15.1 (CH3), two aromatic CH, one CH2 and two CH3 signals were not recognized due to overlapping; HRMS (ESITOF) m/z [M + H]+ calcd for C32H3779BrN 514.2104, found 514.2086. (+)-(P)-3-Bromo-12d-methyl-4b,8b,12b-tripropyl-4b,8b,12b,12dtetrahydrodibenzo[2,3:4,5]pentaleno[1,6-ab]inden-2-amine [(+)-(P)-5]. According to the method described above, the diastereomer (+)-(P,S)-11 (278 mg, 0.34 mmol) was stirred in the mixture of acetone (6 mL) and aqueous hydrochloric acid solution (HCl, 6 M, 2 mL) for 46 h. Workup followed by flash column chromatography (petroleum ether/EtOAc = 50/1) of the residue through silica gel afforded ortho-bromo-TBTQ-amine (+)-(P)-5 (156 mg, 89%) as a colorless solid: mp 223−226 °C; Rf 0.5 (petroleum ether/EtOAc = 4/1); [α]D25 +4.0 (c 0.5, CH2Cl2); 1H NMR (400 MHz, CDCl3, 25 °C) δ = 7.302−7.283 (m, 2H), 7.275 (s, 1H), 7.23− 7.21 (m, 2H), 7.15−7.11 (m, 4H), 6.67 (s, 1H), 3.68 (br s, 2H), 2.15− 2.06 (m, 6H), 1.58 (s, 3H), 1.23−1.13 (m, 6H), 0.94−0.90 (m, 9H); 13 C NMR (100 MHz, CDCl3, 25 °C) δ = 148.7 (C), 148.1 (C), 148.0 (C), 147.8 (C), 147.6 (C), 142.6 (C), 140.5 (C), 127.28 (CH), 127.25 (CH), 127.1 (CH), 127.0 (CH), 123.4 (CH), 123.3 (CH), 123.1 (CH), 110.2 (CH), 109.3 (C), 72.1 (C), 67.2 (C), 66.9 (C), 66.5 (C), 40.91 (CH2), 40.86 (CH2), 40.6 (CH2), 20.43 (CH2), 20.35 (CH2), 15.2 (CH3), 15.1 (CH3), two aromatic CH, one CH2 and two CH3 signals were not recognized due to overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C32H3779BrN 514.2104, found 514.2088.

overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C32H38N 436.2999, found 436.3003. (±)-3-Bromo-12d-methyl-4b,8b,12b-tripropyl-4b,8b,12b,12dtetrahydrodibenzo[2,3:4,5]pentaleno[1,6-ab]inden-2-amine [(±)-5]. N-Bromosuccinimide (427 mg, 2.40 mmol) was added to a stirred solution of TBTQ-amine (±)-9 (871 mg, 2.00 mmol) in acetonitrile (25 mL). The resulting mixture was heated to reflux for 4.5 h. The reaction was monitored by TLC. Upon completion of the reaction, the solvent was removed under reduced pressure. The resulting residue was dissolved in water/ethyl acetate (1/1, 20 mL), and the aqueous layer was extracted with ethyl acetate (3 × 10 mL). The combined organic layers were washed with saturated aqueous Na2S2O3 solution (15 mL) and brine, dried over Na2SO4, filtered, and concentrated under reduced pressure. Flash column chromatography of the residue through silica gel (petroleum ether/EtOAc = 50/1) afforded orthobromo-TBTQ-amine (±)-5 (1.01 g, 98%) as a pale-yellow solid: mp 228−230 °C; Rf 0.5 (petroleum ether/EtOAc = 4/1); 1H NMR (400 MHz, CDCl3, 25 °C) δ = 7.304−7.283 (m, 2H), 7.275 (s, 1H), 7.24− 7.20 (m, 2H), 7.14−7.12 (m, 4H), 6.63 (s, 1H), 3.75 (br s, 2H), 2.15− 2.06 (m, 6H), 1.58 (s, 3H), 1.22−1.13 (m, 6H), 0.94−0.89 (m, 9H); 13 C NMR (100 MHz, CDCl3, 25 °C) δ = 148.7 (C), 148.1 (C), 148.0 (C), 147.8 (C), 147.6 (C), 142.8 (C), 140.4 (C), 127.28 (CH), 127.25 (CH), 127.1 (CH), 126.9 (CH), 123.4 (CH), 123.3 (CH), 123.1 (CH), 110.1 (CH), 109.2 (C), 72.1 (C), 67.1 (C), 66.9 (C), 66.5 (C), 40.9 (CH2), 40.8 (CH2), 40.6 (CH2), 20.4 (CH2), 20.3 (CH2), 15.12 (CH3), 15.11 (CH3), two aromatic CH, one CH2 and two CH3 signals were not recognized due to overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C32H3779BrN 514.2104, found 514.2085. Optical Resolution Procedure of (±)-5. (S)-2,2′-Dihydroxy[1,1′-binaphthalene]-3-carbaldehyde [(S)-10, 295 mg, 0.94 mmol] and Cs2CO3 (508 mg, 1.56 mmol) were added to a stirred solution of (±)-5 (401 mg, 0.78 mmol) in dichloromethane (40 mL). The mixture was heated to reflux for 35 h. The reaction was monitored by TLC. Upon completion of the reaction, the solvent was removed under reduced pressure. Flash column chromatography (petroleum ether/CH2Cl2/EtOAc = 30/10/1) of the residue through silica gel (prewashed with petroleum ether/Et3N = 100/1 before loading the sample) afforded the bright-yellow diastereomer (−)-(M,S)-11 (259 mg, 41%) as the first-eluting fraction (Rf 0.3, petroleum ether/EtOAc = 2/1) and (+)-(P,S)-11 (278 mg, 44%) as the second-eluting fraction (Rf 0.2, petroleum ether/EtOAc = 2/1). (Note: Soaking of the silica gel in petroleum ether/Et3N = 100/1 and subsequent drying under air at ambient temperature is necessary.) (−)-(M,S)-3-Bromo-2-(((2,2′-dihydroxy-[1,1′-binaphthalen]-3-yl)methylene)amino)-12d-methyl-4b,8b,12b-tripropyl-4b,8b,12b,12dtetrahydrodibenzo[2,3:4,5]pentaleno[1,6-ab]indene [(−)-(M,S)-11]: Bright-yellow solid; mp 197−199 °C; [α]D25 −372.0 (c 0.5, CH2Cl2); 1 H NMR (600 MHz, acetone-d6, 25 °C, the signal of the nonhydrogen bonded phenolic H may merge with the residual water signal located at δ = 2.85) δ = 12.80 (br s, 1H), 9.25 (s, 1H), 8.36 (s, 1H), 8.01−7.99 (m, 1H), 7.91 (d, J = 9.0 Hz, 1H), 7.84 (d, J = 8.4 Hz, 1H), 7.83 (s, 1H), 7.81 (s, 1H), 7.62−7.61 (m, 1H), 7.53−7.52 (m, 1H), 7.48−7.46 (m, 2H), 7.37 (d, J = 9.0 Hz, 1H), 7.34−7.31 (m, 2H), 7.23 (ddd, J = 7.8, 6.6, and 1.2 Hz, 1H), 7.17−7.08 (m, 7H), 2.34−2.23 (m, 6H), 1.71 (s, 3H), 1.28−1.20 (m, 6H), 0.96−0.92 (m, 9H); 13C NMR (150 MHz, acetone-d6, 25 °C) δ = 164.7 (CH), 156.3 (C), 153.9 (C), 150.5 (C), 150.4 (C), 149.21 (C), 149.18 (C), 148.3 (C), 148.2 (C), 146.5 (C), 137.2 (C), 136.6 (CH), 135.3 (C), 130.2 (CH), 130.0 (CH), 129.9 (C), 129.6 (CH), 128.9 (CH), 128.77 (C), 128.76 (CH), 128.32 (CH), 128.28 (CH), 126.9 (CH), 125.6 (CH), 125.54 (CH), 124.51 (CH), 124.47 (CH), 124.41 (CH), 124.36 (CH), 123.5 (CH), 122.5 (C), 119.9 (C), 119.4 (CH), 117.3 (C), 116.0 (C), 115.2 (CH), 73.0 (C), 68.4 (C), 68.2 (C), 68.0 (C), 41.4 (CH2), 41.3 (CH2), 41.2 (CH2), 21.29 (CH2), 21.26 (CH2), 21.2 (CH2), 15.7 (CH3), 15.3 (CH3), 15.2 (CH3), three aromatic CH signals and one CH3 signal were not recognized due to overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C53H4979BrNO2 810.2941, found 810.2947. (+)-(P,S)-3-Bromo-2-(((2,2′-dihydroxy-[1,1′-binaphthalen]-3-yl)methylene)amino)-12d-methyl-4b,8b,12b-tripropyl-4b,8b,12b,12dtetrahydrodibenzo[2,3:4,5]pentaleno[1,6-ab]indene [(+)-(P,S)-11]: 3438

DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440

The Journal of Organic Chemistry

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syn-22d,22e-Dimethyl-4b,8b,11b,15b,19b,22b-hexapropyl4b,8b,11b,15b,19b,22b,22d,22e-octahydrobisbenzo[5,6]-indeno[1′,2′,3′:3,4]pentaleno[1,2-b:1′,2′-i]phenazine (syn-6). Into a flamedried, Ar-purged round-bottom flask were sequentially added (−)-(M)-5 (51 mg, 0.10 mmol), Cs2CO3 (130 mg, 0.40 mmol), Pd(OAc)2 (2.2 mg, 0.01 mmol), and dicyclohexyl-(2′,6′-diisopropoxy[1,1′-biphenyl]-2-yl)phosphine (RuPhos, 9.3 mg, 0.02 mmol). Dry, degassed toluene (40 mL) was then added. The mixture was heated to reflux under Ar for 3.5 h. Then it was cooled to room temperature and concentrated under reduced pressure. Flash column chromatography of the residue (petroleum ether/EtOAc = 100/1) through silica gel afforded bis-TBTQ-phenazine syn-6 (26 mg, 60%) as a yellow solid: mp >350 °C; Rf 0.46 (petroleum ether/EtOAc = 5/1); 1H NMR (400 MHz, CDCl3, 25 °C) δ = 8.09 (s, 4H), 7.47−7.45 (m, 4H), 7.30−7.28 (m, 4H), 7.14−7.12 (m, 8H), 2.38−2.19 (m, 12H), 1.70 (s, 6H), 1.27−1.22 (m, 12H), 0.96−0.93 (m, 18H); 13C NMR (100 MHz, CDCl3, 25 °C) δ = 154.5 (C), 148.0 (C), 147.0 (C), 142.9 (C), 127.7 (CH), 123.8 (CH), 123.3 (CH), 122.2 (CH), 72.1 (C), 67.9 (C), 67.0 (C), 42.0 (CH2), 40.6 (CH2), 20.5 (CH2), 20.4 (CH2), 15.4 (CH3), 15.2 (CH3), 15.1 (CH3), one aromatic CH signal was not recognized due to overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C64H69N2 865.5455, found 865.5464. Using the same procedure, (+)-(P)-5 (51 mg, 0.10 mmol) could be converted to syn-6 (27 mg, 62%); HRMS (ESI-TOF) m/z [M + H]+ calcd for C64H69N2 865.5455, found 865.5491. The 1H and 13C NMR spectroscopic of the product were identical to those of the sample obtained from (−)-(M)-5. anti-22d,22e-Dimethyl-4b,8b,11b,15b,19b,22b-hexapropyl4b,8b,11b,15b,19b,22b,22d,22e-octahydrobisbenzo[5,6]-indeno[1′,2′,3′:3,4]pentaleno[1,2-b:1′,2′-i]phenazine (anti-6). Into a flamedried, Ar-purged round-bottom flask were sequentially added (±)-5 (62 mg, 0.12 mmol), Cs2CO3 (156 mg, 0.48 mmol), Pd(OAc)2 (2.7 mg, 0.012 mmol), and RuPhos (11.2 mg, 0.024 mmol). Dry, degassed toluene (40 mL) was then added. The mixture was refluxed under Ar for 3.5 h. Then it was cooled to room temperature and concentrated under reduced pressure. Flash column chromatography of the residue (petroleum ether/EtOAc = 100/1) through silica gel afforded bisTBTQ-phenazine anti-6 (18 mg, 35%) as a yellow solid and bisTBTQ-phenazine syn-6 (15 mg, 29%) as a yellow solid. Compound anti-6: mp >350 °C; Rf = 0.44 (petroleum ether/EtOAc = 5/1); 1H NMR (400 MHz, CDCl3, 25 °C) δ = 8.08 (s, 4H), 7.49−7.46 (m, 4H), 7.32−7.30 (m, 4H), 7.16−7.14 (m, 8H), 2.35−2.19 (m, 12H), 1.69 (s, 6H), 1.27−1.20 (m, 12H), 0.97−0.90 (m, 18H); 13C NMR (100 MHz, CDCl3, 25 °C) δ = 154.5 (C), 148.1 (C), 147.1 (C), 142.9 (C), 127.6 (CH), 123.8 (CH), 123.3 (CH), 122.2 (CH), 72.1 (C), 67.9 (C), 67.0 (C), 41.9 (CH2), 40.6 (CH2), 20.5 (CH2), 20.4 (CH2), 15.4 (CH3), 15.13 (CH3), 15.10 (CH3), one aromatic CH signal was not recognized due to overlapping; HRMS (ESI-TOF) m/z [M + H]+ calcd for C64H69N2 865.5455, found 865.5471.

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. *E-mail: [email protected]. ORCID

Zhi-Min Li: 0000-0001-8107-3399 Ya-Wei Li: 0000-0002-9823-3982 Xiao-Ping Cao: 0000-0001-8340-1122 Hak-Fun Chow: 0000-0002-7621-0851 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors are grateful for financial support from the National Natural Science Foundation of China (Grant Nos. 21572085 and 21272098), FRFCU (lzujbky-2016-ct02), PCSIRT (IRT_15R28), the 111 Project of MOE (111-2-17), and the RGC of HKSAR (Project No. 14303816). We thank YongLiang Shao of Lanzhou University for X-ray crystallographic analyses.

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REFERENCES

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.8b00375. 1 H and 13C NMR spectra of all new compounds, chiral HPLC analyses of (−)-(M)-5 and (+)-(P)-5, X-ray crystallography of (−)-(M)-5, (+)-(P)-5, syn-6 and anti6, UV spectra of (±)-5, phenazine, syn-6 and anti-6, emission spectra of phenazine, anti-6, and syn-6, electrospray high-resolution mass spectra of (−)-(M,S)11 and (+)-(P,S)-11, computational results of anti-6 and syn-6 (PDF) X-ray crystallographic data for (−)-(M)-5 (CIF) X-ray crystallographic data for (+)-(P)-5 (CIF) X-ray crystallographic data for syn-6 (CIF) X-ray crystallographic data for anti-6 (CIF) 3439

DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440

The Journal of Organic Chemistry

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triquinacene (TBTQ) Derivative. Chem. - Asian J. 2015, 10, 1150− 1158. (5) (a) Strübe, J.; Neumann, B.; Stammler, H.-G.; Kuck, D. SolidState Enantiopure Organic Nanocubes Formed by Self Organization of a C3-Symmetrical Tribenzotriquinacene. Chem. - Eur. J. 2009, 15, 2256−2260. (b) Klotzbach, S.; Scherpf, T.; Beuerle, F. Dynamic Covalent Assembly of Tribenzotriquinacenes into Molecular Cubes. Chem. Commun. 2014, 50, 12454−12457. (c) Klotzbach, S.; Beuerle, F. Shape-Controlled Synthesis and Self-Sorting of Covalent Organic Cage Compounds. Angew. Chem., Int. Ed. 2015, 54, 10356−10360. (d) Dhara, A.; Beuerle, F. Reversible Assembly of a Supramolecular Cage Linked by Boron-Nitrogen Dative Bonds. Chem. - Eur. J. 2015, 21, 17391−17396. (e) Beuerle, F.; Klotzbach, S.; Dhara, A. Let’s Sort It Out: Self-Sorting of Covalent Organic Cage Compounds. Synlett 2016, 27, 1133−1138. (f) Beuerle, F.; Gole, B. Covalent Organic Frameworks and Cage Compounds: Design and Applications of Polymeric and Discrete Organic Scaffolds. Angew. Chem., Int. Ed. 2017, DOI: 10.1002/anie.201710190. (6) Beaudoin, D.; Rominger, F.; Mastalerz, M. Chirality-Assisted Synthesis of a Very Large Octameric Hydrogen-Bonded Capsule. Angew. Chem., Int. Ed. 2016, 55, 15599−15603. (7) Beaudoin, D.; Rominger, F.; Mastalerz, M. Chiral Self-Sorting of [2 + 3] Salicylimine Cage Compounds. Angew. Chem., Int. Ed. 2017, 56, 1244−1248. (8) Henne, S.; Bredenkötter, B.; Baghi, A. A. D.; Schmid, R.; Volkmer, D. Advanced Buckyball Joints: Synthesis, Complex Formation and Computational Simulations of CentrohexaindaneExtended Tribenzotriquinacene Receptors for C60 Fullerene. Dalton Trans. 2012, 41, 5995−6002. (9) Ip, H.-W.; Chow, H.-F.; Kuck, D. Electronic and Steric Effects on the Three-Fold Scholl-Type Cycloheptatriene Ring Formation around a Tribenzotriquinacene Core. Org. Chem. Front. 2017, 4, 817−822. (10) Xu, W.-R.; Xia, G.-J.; Chow, H.-F.; Cao, X.-P.; Kuck, D. Facile Assembly of Chiral Metallosquares by Using Enantiopure Tribenzotriquinacene Corner Motifs. Chem. - Eur. J. 2015, 21, 12011−12017. (11) (a) Mastalerz, M. Permanent Porous Materials from Discrete Organic Molecules − Towards Ultra-High Surface Areas. Chem. - Eur. J. 2012, 18, 10082−10091. (b) Elbert, S. M.; Rominger, F.; Mastalerz, M. Synthesis of a Rigid C3v-Symmetric Tris-salicylaldehyde as a Precursor for a Highly Porous Molecular Cube. Chem. - Eur. J. 2014, 20, 16707−16720. (c) Liu, Z.; Nalluri, S. K. M.; Stoddart, J. F. Surveying Macrocyclic Chemistry: from Flexible Crown Ethers to Rigid Cyclophanes. Chem. Soc. Rev. 2017, 46, 2459−2478. (12) Niu, W.-X.; Yang, E.-Q.; Shi, Z.-F.; Cao, X.-P.; Kuck, D. SingleWing Extended Tribenzotriquinacenes via Bowl-Shaped Dehydrobenzene and Isobenzofuran Tribenzotriquinacene Derivatives. J. Org. Chem. 2012, 77, 1422−1434. (13) Saravanakumar, R.; Markopoulos, G.; Bahrin, L. G.; Jones, P. G.; Hopf, H. The Regiospecific Preparation of 2-Substituted Tribenzotriquinacenes. Synlett 2013, 24, 453−456. (14) Liu, X.; Weinert, Z. J.; Sharafi, M.; Liao, C.; Li, J.; Schneebeli, S. T. Regulating Molecular Recognition with C-Shaped Strips Attained by Chirality-Assisted Synthesis. Angew. Chem., Int. Ed. 2015, 54, 12772−12776. (15) Mastalerz, M. Single-Handed Towards Nanosized Organic Molecules. Angew. Chem., Int. Ed. 2016, 55, 45−47. (16) (a) Wang, T.; Hou, Q.-Q.; Teng, Q.-F.; Yao, X.-J.; Niu, W.-X.; Cao, X.-P.; Kuck, D. Tribenzotriquinacenes Based on Regioselective Bis-formylation: Optical Resolution and Absolute Configuration of Inherently Chiral Derivatives and Synthesis of the First CyclophaneType Tribenzotriquinacene Dimers. Chem. - Eur. J. 2010, 16, 12412− 12424. (b) Niu, W.-X.; Wang, T.; Hou, Q.-Q.; Li, Z.-Y.; Cao, X.-P.; Kuck, D. Synthesis and Optical Resolution of Inherently Chiral Difunctionalized Tribenzotriquinacenes. J. Org. Chem. 2010, 75, 6704−6707. (17) (a) Beaudoin, D.; Rominger, F.; Mastalerz, M. Synthesis and Chiral Resolution of C3-Symmetric Tribenzotriquinacenes. Eur. J. Org. Chem. 2016, 2016, 4470−4472. (b) Kuck, D.; Linke, J.; Teichmann, L. C.; Barth, D.; Tellenbröker, J.; Gestmann, D.; Neumann, B.; Stammler,

H.-G.; Bögge, H. Centrohexaindane: Six Benzene Rings Mutually Fixed in Three Dimensions − Solid-State Structure and Six-Fold Nitration. Phys. Chem. Chem. Phys. 2016, 18, 11722−11737. (18) Wu, S.; Tang, J.; Han, J.; Mao, D.; Liu, X.; Gao, X.; Yu, J.; Wang, L. Design of C2-Symmetric Salen Ligands and Their Co(II)- or Yb(III)-Complexes, and Their Role in the Reversal of Enantioselectivity in the Asymmetric Henry Reaction. Tetrahedron 2014, 70, 5986−5992. (19) (a) CCDC 1587284 [(−)-(M)-5], 1586447 [(+)-(P)-5], 1586448 (syn-6), and 1586449 (anti-6) contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre. (b) Parsons, S.; Flack, H. D.; Wagner, T. Use of Intensity Quotients and Differences in Absolute Structure Refinement. Acta Crystallogr., Sect. B: Struct. Sci., Cryst. Eng. Mater. 2013, 69, 249−259. (20) Winkler, J. D.; Twenter, B. M.; Gendrineau, T. Synthesis of Substituted Phenazines via Palladium-Catalyzed Aryl Ligation. Heterocycles 2012, 84, 1345−1353. (21) Zhang, Y.-F.; Tian, W.-F.; Cao, X.-P.; Kuck, D.; Chow, H.-F. oQuinones Derived from Tribenzotriquinacenes: Functionalization of Inner Bay Positions and Use for Single-Wing Extensions. J. Org. Chem. 2016, 81, 2308−2319.

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DOI: 10.1021/acs.joc.8b00375 J. Org. Chem. 2018, 83, 3433−3440