Development of a Telescoped Process for Preparation of N, O

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Development of a Telescoped Process for Preparation of N,O-Chelated Diarylborinates Changwei Guan, lingyun huang, Chao Ren, and Gang Zou Org. Process Res. Dev., Just Accepted Manuscript • DOI: 10.1021/acs.oprd.8b00109 • Publication Date (Web): 22 Jun 2018 Downloaded from http://pubs.acs.org on June 25, 2018

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Organic Process Research & Development

Development of a Telescoped Process for Preparation of N,O-Chelated Diarylborinates Changwei Guan, Lingyun Huang, Chao Ren and Gang Zou*

Department of Fine Chemicals, School of Chemistry & Molecular Engineering, East China University of Science & Technology, 130 Meilong Rd, Shanghai, China KEYWORDS. Chelated diarylborinate, One-pot reaction, Barbier-type condition, Telescoped process

ABSTRACT. A telescoped process has been developed for practical preparation of N,Ochelated four-coordinate diarylborinates via direct reaction of N,O-chelate ligands with diarylborinates solution prepared by removal of magnesium via precipitation from one-pot reaction of aryl bromides, magnesium and tributylborate. Ten N,O-chelated diarylborinates of representative N, O-chelate ligands of 2-picolinic acid, quinolin-8-ol, N-dimethylglycine and amino alcohols were readily obtained in good yields. The telescoped process not only minimizes chemical waste and circumvents tedious purification of diarylborinic acids but also eliminates handling of Grignard reagents and improves compatibility with acid-sensitive groups.

ACS Paragon Plus Environment

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Organic Process Research & Development 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Introduction Chelate-stabilized diarylborinates have found increasing importance in chemical, material and biological sciences in recent years. A variety of four-coordinate O,O- O,N- or N,N-chelated diarylborinates have been recognized as highly potential luminescent organic materials for optoelectronic applications,1-8 in particular as organic light-emitting diodes (OLEDs),9 benefiting from boron-enhanced π-conjugation. 2-Aminoethyl diphenylborinate (APB), the simplest fourcoordinate O,N-chelated diarylborinate, has been identified as universal blockers of transient receptor potential channels.10-12 Diarylborinates of amino alcohols,13-15 amino acids,15,

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2-

picolinic acid,17 and quinolinols18 have been reported to display apoptotic, antibacterial, and antiinflammatory acitivities, respectively. In chemistry, four-coordinate diarylborinates could not only be used as shelf-storable aryl sources,19 but also have been identified as true catalysts in regioselective activation of pyranoside and glycosyl acceptors,20,

21

intermediates in aldol

condensation,22 and catalyst precursors in amide chemistry.23-25 The conventional treatment of triarylboranes (Ar3B) or diarylborinic acids (Ar2B(OH)) with the corresponding chelating ligands represents the most practical way to diarylborinates although alternative approaches have also been developed, e.g. transarylation between coordinatively saturated boron halides and aryl stannanes or silanes,26 arylzinc or aluminum,27 and, very recently, arylboronic acids.28 The high air-sensitivity, strong Lewis acidity, and poor functional group compatibility make triarylboranes (Ar3B) less attractable as diarylboron sources than Ar2B(OH), which are air-compatible and could be readily prepared by reaction of aryl magnesium or lithium halides with trialkyl borates,29 or even more practically by one-pot procedure from aryl bromides, magnesium and trialkylborates30 or sterically demanding


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diisopropylaminoborane.31 However, coordinatively unsaturated diarylborinic acids still undergo slow decomposition during shelf-storage. Further, in many cases, purification of diarylborinic acids is often tedious because of their poor crystalline property and incompatibility with conventional chromatography. Therefore, it is important to improve the diarylborinic acid-based procedure to prepare four-coordinate diarylborinates. Herein, we report a telescoped process for practical preparation of four-coordinate chelated diarylborinates by direct reaction of N,Ochelate ligands with diarylborinate solution prepared by removal of magnesium via precipitation from one-pot reaction of aryl bromides, magnesium and tributylborate under Barbier-type condition. Results and discussion N,O-chelated four-coordinate di(p-tolyl)borinate of 2-picolinic acid, di(p-tolyl)boron picolinate (1), was taken as a model compound to develop synthetic process. Direct treatment of the crude di(p-tolyl)borinic acid prepared by one-pot reaction of 4-bromotoluene, triisopropylborate and magnesium chips in THF gave di(p-tolyl)boron picolinate (1) in 31% overall yield, significantly lower than that (93%) by reaction of authentic di(p-tolyl)borinic acid and 2-picolinic acid (Scheme 1). This prompted us to investigate the quality of diarylborinic acid intermediate from the one-pot process.


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Scheme 1. Initial one-pot preparation of di(p-tolyl)boron picolinate (1) 11

B spectrum indicated that the crude bis(p-tolyl)borinic acid was contaminated by p-

tolylboronic acid (Fig. 1, (a)), which could be reasonably attributed to the steric hindrance of the iso-propyl group. To increase the selectivity of diarylborinic vs arylboronic acids, sterically undemanding trimethylborate (B(OMe)3) was used as the boron source under otherwise identical conditions. The borinic/boronic selectivity was remarkably increased as indicated by

11

B

spectrum (Fig. 1, (b)) although initiation of the reaction appeared to be more difficult than that with B(OiPr)3 because of the presence of a small amount of MeOH in commercial B(OMe)3. The presence of MeOH in the reaction mixture was found be deleterious to the yield and the selectivity of bis(p-tolyl)borinic acid through destroying the in-situ generated p-tolyl magnesium species.


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Figure 1. 11B spectra of the crude bis(p-tolyl)borinic acid from B(OiPr)3 (a), B(OMe)3 (b) and B(OBu)3 (c) and the 11B spectra of p-tolylB(OH)2 (d) and B(OBu)3 (e). The formation of p-tolylboronic acid could be completely suppressed when tributylborate B(OBu)3 was used as the boron source, leading to an excellent selectivity for bis(p-tolyl)borinic acid (Fig. 1, (c)). These results indicated that the properties of boron source, e.g. moisturestability and steric hindrance, should play a more important role in the selective formation of diarylborinates in the one-pot procedure than the conventional approach of Grignard reagents. To release free diarylborinic acids, the reaction mixture containing diarylborinate had to be acidified to pH = 1-2. This procedure not only generated and re-dissolved copious solid intermediates consuming a large amount of dilute 1M HCl(aq.) but also led to the presence of excess acid, which had to be removed before being subjected to N,O-chelate ligands. Therefore, it was tried to directly treat the one-pot reaction mixture, i.e. without hydrolysis, with 2-picolinic acid. Unfortunately, the desired N,O-chelated four-coordinate diarylborinate (1) appeared to be


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difficult to purify due to the presence of magnesium salts. Accidentally, it was found that magnesium salts (MgX2 and/or Mg(OR)X) in the reaction mixture could be removed as precipitate Mg(OH)2 under non-acidic conditions. Hence, the one-pot reaction mixture was treated with water instead of 1M HCl(aq.) to precipitate magnesium salts. After filtration, equivalent 2-picolinic acid was then added to the diarylborinate solution to give di(p-tolyl)boron picolinate (1) in 75% yield as white crystalline powder (Scheme 2).32

Scheme 2. Telescoped process for preparation of di(p-tolyl)boron picolinate (1) The yield even slightly increased to 77% when the preparation was conducted in 1.0 kilogram scale with respect to 4-bromotoluene. Therefore, a scalable telescoped process,33 consisting of a one-pot reaction of arylbromides, tributylborate, and magnesium under Barbiertype condition followed by removal of magnesium precipitate and treatment with N,O-chelate ligands, has been developed for practically preparing N,O-chelated four-coordinate diarylborinates. The generality of the telescoped process was also investigated (Scheme 3).


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Scheme 3. Scope and limitation of the telescoped process for preparation of N,O-chelated fourcoordinate diarylborinates

Br R

R

1) 0.5equiv.B(OiPr) 3 1.2equiv. Mg 0.1equiv.(CH2Br)2

R 0.5 equiv. O,N-chelate

B OBu

O B

THF, N2, 40oC, 3h 2) H2O removal of Mg(OH)2

N R

Me

O

O

Me

Me

Me

Me 3, 72%

N

N

N

Me 2, 88%

B

B

B N

O

O

O

B H2N

Me

Me

Me

Me

B

R

4, 64%

Me

5, 56%

6, 65%

F3C O

O

O

B

B N

Me 7, 62%

O

O

O

B

N

O

O O

O

B N

N

O O

F3C 8, 78%

9, 65%

10, 59%

A series of N,O-chelated four-coordinate di(p-tolyl)borinates were prepared in good yields with representative ligands, e.g. ethanolamine (2, 88%), dimethylethanolamine (3, 72%), 3-(dimethylamino)propanol (4, 64%), pyridin-2-ylmethanol (5, 56%), quinolin-8-ol (6, 65%) and dimethyl glycine (7, 62%). Isolation of di(phenyl)boron picolinate 8 in good yield (78%) clearly demonstrated the advantages of the telescoped process since the intermediate di(phenyl)borinic acid (Ph2B(OH)) is not only difficult to purify but also troublesome in characterization and stoichiometry because of dehydration. Similarly, di(4-(trifluoromethyl)phenyl)boron picolinate 9


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could be obtained in 75% yield confirming the feasibility of this telescoped procedure considering

the

Grignard

reagent

p-CF3C6H4MgBr

for

preparation

of

di(trifloromethylphenyl)borinic acid in conventional way is thermal sensitive, decomposing above 40oC.34 The compatibility of acid-sensitive and sterically demanding aryl group of the telescoped process was demonstrated in the preparation of (di(2-(1,3-dioxolan-2-yl)phenyl)boron picolinate 10 in 65% yield, in which the ortho-cyclic acetal group survived. However, when 4bromobenzonitrile or 4-bromoacetophone was used as original aryl source no N,O-chelated fourcoordinate diarylborinate could be obtained, possibly due to the incompatibility of CN and Ac groups with the in situ generated aryl magnesium species.

Conclusion In summary, we have developed a practical and telescoped process for the preparation of fourcoordinate diarylborinates in good yields by direct treatment of N,O-chelate ligands with diarylborinates solution prepared by removal of magnesium via precipitation and filtration from one-pot reaction of aryl bromides, magnesium and tributylborate in THF under Barbier condition. The key for success of the telescoped process lies in choice of proper trialkylboronate, i.e. tributylboronate, as boron source as well as the removal of magnesium salts by precipitating under non-acidic conditions. Advantages of the telescoped process include eliminating utility of Grignard reagents, circumventing tedious purification of diarylborinic acid intermediates, minimizing chemical waste and improving acid-sensitive group compatibility, which were demonstrated in preparation of ten representative N,O-chelated diarylborinates, including di(phenyl)boron,

di(trifloromethylphenyl)boron

and

di(2-(1,3-dioxolanyl)phenyl)boron

picolinates in good yields.


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Experimental section General Information. All reactions were carried out under a nitrogen atmosphere unless otherwise stated. Commercially available chemicals, including THF (>99%), were used as received. 1H,

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C and

11

B NMR spectra were recorded in CDCl3 or DMSO-d6 at ambient

temperature. Chemical shifts in NMR were reported in ppm (δ), relative to CDCl3 or DMSO-d6. The signals observed were described as s (singlet), d (doublet), t (triplet), q (quartet), dd (double doublet), dt (double triplet), m (multiplets). The number of protons (n) for a given resonance was indicated as nH. Coupling constants were reported as J in Hz. The O, N-chelated diarylborinates were identified by 1H and 13C NMR, among which the new compounds 5, 7 and 10 were further characterized by HRMS. General Procedure for preparation of O, N-chelated diarylborinates To a stirred mixture of magnesium chips (3.0 g, 120 mmol) in THF (30 mL) was added 1,2dibromoethane (0.95g, 5 mmol) in one port at 40 °C under N2 atmosphere to activate magnesium, followed by dropwise addition of a mixture of B(OBu)3 (50 mmol), aryl bromide (100 mmol) and the second part of 1,2-dibromoethane (0.95g, 5 mmol) in 50 mL of THF over a period of 45 min. The reaction was maintained at 40-50 °C for another 2h (about 3h in total) before being cooled to room temperature. Then, 20 mL water was added to precipitate magnesium ion and the resulting cloudy solution was stirred for 3 hours at room temperature to give a suspension. Filtration of the suspension with aid of Celite or more readily, centrifugation and decantation, to remove the precipitate (Mg(OH)2 gave a clear solution, to which N,O-chelate ligand (50 mmol) was added to form the desired O, N-chelated diarylborinate. After stirring for 2 hours, organic volatiles, solvent THF and BuOH, were removed by rotavapor from the resulting


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suspension to provide the diarylborinate, which could be purified by re-crystallization in hot MeOH if necessary. Di(p-tolyl)boron picolinate (1). White crystalline powder (11.80 g, 75%), m.p.: 163-165 oC; 1H NMR (CDCl3, 400 MHz) δ (ppm): 8.67 (d, J = 5.2 Hz, 1H), 8.32 (d, J = 1.2 Hz, 1H), 8.31 (d, J = 0.8 Hz, 1H), 7.88-7.84 (m, 1H), 7.26 (d, J = 8.0 Hz, 4H), 7.25 (d, J = 7.6 Hz, 4H), 2.30 (s, 6H); 13

C NMR (CDCl3, 100 MHz) δ (ppm): 163.4, 143.3, 143.1, 141.8, 137.1, 132.2, 128.9, 128.6,

123.7, 21.2. 2-Aminoethyl di(p-tolyl)borinate (2). White crystalline powder (11.13 g, 88%), m.p.: 180-182 o

C; 1H NMR (DMSO-d6, 400 MHz) δ (ppm):7.26 (d, J = 7.6 Hz, 4H), 6.94 (d, J = 7.6 Hz, 4H),

5.93 (s, 2H), 3.75 (t, J = 6.8 Hz, 2H), 2.82-2.76 (m, 2H), 2.20 (s, 6H);13C NMR (DMSO-d6, 100 MHz) δ (ppm): 133.2, 131.5, 127.2, 62.3, 41.2, 20.8. 2-Dimethylaminoethyl di(p-tolyl)borinate (3). White crystalline powder (10.12g, 72%), m.p.: 156-158 oC; 1H NMR (CDCl3, 400 MHz) δ (ppm): 7.62 (d, J = 8.0 Hz, 4H), 7.08 (d, J = 7.6 Hz, 4H), 4.24 (t, J = 7.2 Hz, 2H), 2.84 (t, J = 6.8 Hz, 2H), 2.51 (s, 6H), 2.28 (s, 6H);

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C NMR

(CDCl3, 100 MHz) δ (ppm): 135.3, 132.5, 128.0, 60.6, 60.3, 47.0, 21.2. 3-Dimethylaminopropyl di(p-tolyl)borinate (4) White crystalline powder (9.45 g, 64%), m.p.: 104-105 oC; 1H NMR (CDCl3, 400 MHz) δ (ppm): 7.39 (d, J = 6.0 Hz, 4H), 7.01 (d, J = 7.6 Hz, 4H), 3.74 (t, J = 5.6 Hz, 2H), 3.00 (t, J = 5.6 Hz, 2H), 2.43 (s, 6H), 2.24 (s, 6H), 1.78-1.72 (m, 2H);

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20.2. Pyridin-2-ylmethyl di(p-tolyl)borinate (5) White crystalline powder (8.43 g, 56%), m.p.: 143145 oC; 1H NMR (CDCl3, 400 MHz) δ (ppm): 8.39 (d, J = 5.6 Hz, 1H), 7.95 (dt, J1 = 1.2 Hz, J2 = 7.6 Hz, 1H), 7.50 (d, J = 8.0 Hz, 1H), 7.45 (t, J = 6.4 Hz, 1H), 7.30 (d, J = 7.6 Hz, 4H), 7.08 (d, J


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= 7.6 Hz, 4H), 5.28 (s, 2H), 2.30 (s, 6H);

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C NMR (CDCl3, 100 MHz) δ (ppm): 159.4, 141.2,

140.5, 135.8, 132.7, 128.1, 123.8, 120.0, 68.9, 21.3; HRMS (ESI) m/z [M+1]+ calcd for C20H21BNO 302.1716, found 302.1717. Di(p-tolyl)boron 8-hydroxyquinolinate (6) Yellow crystalline powder (10.95 g, 65%), mp: 202-203 oC; 1H NMR (CDCl3, 400 MHz) δ (ppm): 8.53 (dd, J1 = 0.8 Hz, J2 = 4.8 Hz, 1H), 8.33 (d, J1 = 0.8 Hz, J2 = 8.4 Hz, 1H), 7.64 (t, J = 8.0 Hz, 1H), 7.56-7.53 (m, 1H), 7.35 (d, J = 8.0 Hz, 4H), 7.20 (d, J = 8.4 Hz, 1H), 7.15 (d, J = 7.6 Hz, 1H), 7.09 (d, J = 7.6 Hz, 4H), 2.29 (s, 6Hz); 13


122.8, 112.1, 109.6, 21.3. Di(p-tolyl)boron dimethylglycinate (7) White crystalline powder (9.15 g, 62%), mp: 195-197 o

C; 1H NMR (CDCl3, 400 MHz) δ (ppm): 7.57 (d, J = 7.6 Hz, 4H), 7.12 (d, J = 7.6 Hz, 4H), 3.39

(s, 2H), 2.56 (s, 6H), 2.29 (s, 6H);

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C NMR (CDCl3, 100 MHz) δ (ppm): 170.1, 136.8, 132.0,

128.6, 62.9, 48.6, 21.2; HRMS (ESI) m/z [M+1]+ calcd for C18H23BNO2 296.1822, found 296.1824. Diphenylboron picolinate (8) White crystalline powder (11.21 g, 78%); mp.: 165-167 oC; 1H NMR (CDCl3, 400 MHz) δ(ppm): 8.66 (d, J = 5.6 Hz, 1H), 8.31 (t, J = 2.4 Hz, 2H), 7.86 (q, J = 5.6 Hz, 1H), 7.35-7.36 (m, 4H), 7.25-7.26 (m, 6H)；13C NMR (CDCl3, 100 MHz) δ(ppm)： 163.5, 143.4, 143.2, 141.9, 132.2, 129.1, 127.9, 127.6, 123.9. Di(4-(trifluoromethyl)phenyl)boron picolinate (9) White crystalline powder (15.81 g, 75%), mp: 152-153 oC; 1H NMR (CDCl3, 400 MHz) δ (ppm): 9.35 (d, J = 5.6 Hz, 1H), 8.72 (dt, J1 = 1.2 Hz, J2 = 7.6 Hz, 1H), 8.54 (d, J = 7.6 Hz, 1H), 8.29-8.26 (m, 1H), 7.64-7.56 (m, 8H);

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C

NMR (CDCl3, 100 MHz) δ (ppm): 163.5, 145.8, 143.4, 142.0, 132.9, 131.2, 128.3 (q, J = 31.2 Hz), 126.3, 124.8, 124.5 (q, J = 3.8 Hz), 123.6.


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Di(2-(1,3-dioxolan-2-yl)phenyl)boron picolinate (10) White crystalline powder (14.01 g, 65%), m.p.: 156-157 oC; 1H NMR (CDCl3, 400 MHz) δ (ppm): 8.89 (d, J = 5.2 Hz, 1H), 8.65 (t, J = 7.2 Hz, 1H), 8.45 (d, J = 7.6 Hz, 1H), 8.17 (t, J = 6.4 Hz, 1H), 7.50 (d, J = 7.2 Hz, 2H), 7.27-7.17 (m, 4H), 6.92 (d, J = 7.2 Hz, 2H), 5.75 (s, 2H), 3.91-3.85 (m, 2H), 3.79-3.73 (m, 2H), 3.66-3.57 (m, 4H); 13C NMR (CDCl3, 100 MHz) δ (ppm): 163.4, 145.2, 144.1, 143.6, 140.8, 132.4, 130.0, 128.4, 127.4, 126.3, 123.7, 101.8, 64.9, 64.8; HRMS (ESI) m/z [M+Na]+ calcd for C24H22BNO6Na 454.1438, found 454.1446. Large scale preparation of di(p-tolyl)boron picolinate (1) To 10 L cylindrical shaped reactor of jacket glass reaction kettle were added 170.0 g (7.1 mol) magnesium chips, 1.5 L THF, 1.0 g iodine (indicator for initiation) and 50.0 g (0.27 mol) 1,2-dibromoethane under nitrogen. The mixture was stirred (about 150 rpm) at 40 °C for 10 min to activate magnesium. Then, a small portion (100 mL) of a mixture of 1.0 Kg (5.85 mol) 4bromotoluene, 678 g (2.95 mole) B(OBu)3, and the second part of 1,2-dibromoethane (50.0 g, 0.27 mol) in 3.0 L THF was added. When the yellow-brown color of the mixture disappeared, the remaining THF solution (3 L) was added (slowly running in) over a period of 2 h. The reaction temperature slightly increased to 50 °C, at which the reaction was maintained for another 3 h (about 5 h in total) before being cooled to room temperature. Then, 1.0 L water was added and the resulting suspension was stirred for 2 hours at room temperature. The resulting suspension was transferred to a centrifugal filter with polypropylene filter cloth and filtrated to remove Mg(OH)2, which was rinsed with THF (2 x 0.5 L). The total filtrate (~ 7 L) was reloaded to the 10 L cylindrical shaped reactor and 363.0 g (2.95 mol) 2-picolinic acid was added in one-portion. The mixture was stirred for 2h and then concentrated by distillation at 70-80 oC until ~ 4.5 L THF (contaminated by BuOH) was collected. After cooling to room temperature,


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the resulting suspension was filtered, washed with water and dried in vacuum at 80 oC to afford di(p-tolyl)boron picolinate 1 (715 g, 77%) as white thin needles, with purity >98.5% by HPLC.

ASSOCIATED CONTENT Supporting Information. The Supporting Information is available free of charge on the ACS Publications website at DOI: 1

H and 13C NMR, HRMS (new compounds) of diarylboronates, photo pictures of the scale-up

reactor, and HPLC of 1 prepared in kilogram scale (PDF). AUTHOR INFORMATION Corresponding Author E-mail: [email protected]. Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. ACKNOWLEDGMENT We thank the National Natural Science Foundation of China (21472041) and National Key Technology R&D Program, the Ministry of Science and Technology of China (2015BAK44B00) for financial support. Notes The authors declare no competing financial interest.


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REFERENCES (1) Rao, Y.-L.; Wang, S. Four-coordinate Organoboron Compounds with a π-Conjugated Chelate Ligand for Optoelectronic Applications, Inorg. Chem. 2011, 50, 12263-12274. (2) Frath, D.; Massue, J.; Ulrich, G.; Ziessel, R. Luminescent Materials: Locking π-Conjugated and Heterocyclic Ligands with Boron(III), Angew. Chem. Int. Ed. 2014, 53, 2290-2310. (3) Wakamya, A.; Yamaguch, S. Designs of Functional π-Electron Materials based on the Characteristic Features of Boron, Bull. Chem. Soc. Jpn. 2015, 88, 1357-1377. (4) Tanaka, K.; Chujo, Y. Recent Progress of Optical Functional Nanomaterials Based on Organoboron Complexes with β-Diketonate, Ketoiminate and Diiminate, NPG Asia Mater. 2015, 7, e223. (5) Zhang, Z.; Zhang, H.; Jiao, C.; Ye, K.; Zhang, H.; Zhang, J.; Wang, Y. 2-(2Hydroxyphenyl)benzimidazole-Based Four-Coordinate Boron-Containing Materials with Highly Efficient Deep-Blue Photoluminescence and Electroluminescence, Inorg. Chem. 2015, 54, 26522659. (6) Wesela-Bauman, G.; Urban, M.; Luliński, S.; Serwatowskia, J.; Woźniak, K. Tuning of the Colour and Chemical Stability of Model Boranils: A Strong Effect of Structural Modifications, Org. Biomol. Chem. 2015, 13, 3268-3279. (7) Más-Montoya, M.; Usea, L.; Ferao, A. E.; Montenegro, M. F.; de Arellano, C. R.; Tárraga, A.; Rodríguez-López, J. N.; Curiel, D. Single Heteroatom Fine-Tuning of the Emissive Properties in Organoboron Complexes with 7-(Azaheteroaryl)indole Systems, J. Org. Chem. 2016, 81, 3296-3302.


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(8) For a most recent example and references therein see: Qi, Y.; Kang, R.; Huang, J.; Zhang, W.; He, G.; Yin, S.; Fang, Y. Reunderstanding the Fluorescent Behavior of Four-Coordinate Monoboron Complexes Containing Monoanionic Bidentate Ligands. J. Phys. Chem. B. 2017, 121, 6189-6199. (9) For an excellent review see: Li, D.; Zhang, H. Y.; Wang, Y. Four-Coordinate Organoboron Compounds for Organic Light-Emitting Diodes (OLEDs), Chem. Soc. Rev. 2013, 42, 8416-8433. (10) Maruyama, T.; Kanaji, T.; Nakade, S.; Kanno, T.; Mikoshiba, K. 2APB, 2Aminoethoxydiphenyl Borate, a Membrane-Penetrable Modulator of Ins(1,4,5)P3-Induced Ca2+ Release , J. Biochem. 1997, 122, 498-505. (11) Colton, C. K.; Zhu, M. X. 2-Aminoethoxydiphenyl Borate as a Common Activator of TRPV1, TRPV2, and TRPV3 Channels, Handbook Exp Pharmacol. 2007, 179, 173-187. (12) Kühn, F. J. P.; Mathis, W.; Cornelia, K.; Hoffmann, D. C.; Lückhoff, A. Modulation of Activation and Inactivation by Ca2+ and 2-APB in the Pore of an Archetypal TRPM Channel from Nematostella Vectensis, Sci. Rep. 2017, 7, 7245. (13) Van Rossum, D. B.; Patterson, R. L.; Ma, H. T.; Gill, D. L. Ca2+ Entry Mediated by Store Depletion, S-Nitrosylation, and TRP3 Channels. Comparison of Coupling and Function, J. Biol. Chem. 2000, 275, 28562-28568. (14) Xu, S. Z.; Zeng, F.; Boulay, G.; Grimm, C.; Harteneck, C.; Beech, D. J. Block of TRPC5 Channels by 2-Aminoethoxydiphenyl Borate: A Differential, Extracellular and VoltageDependent Effect, Br. J. Pharmacol. 2005, 145, 405-414.


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(15) Ozaki, S.; Suzuki, A. Z.; Bauer, P. O.; Ediui, E.; Mikoshiba, K. 2-Aminoethyl Diphenylborinate (2-APB) Analogues: Regulation of Ca

2+

Signaling, Biochem. Biophys. Res.

Commun. 2013, 441, 286-290. (16) Velasco, B.; Trujillo-Ferrara, J. G.; Castillo, L. H. F.; Miranda, R.; Sánchez-Torres, L. E. In Vitro Apoptotic Activity of 2,2-Diphenyl-1,3,2-Oxazaborolidin-5-ones in L5178Y Cells, Life Sci. 2007, 80, 1007-1013. (17) Baker, S. J.; Akama, T.; Zhang, Y. K.; Sauro, V.; Pandit, C.; Singh, R.; Kully, M.; Khan, J.; Plattner, J. J.; Benkovic, S. J.; Lee, V.; Maples, K. R. Identification of a Novel BoronContaining Antibacterial Agent (AN0128) with Anti-Inflammatory Activity for the Potential Treatment of Cutaneous Diseases, Bioorg. Med. Chem. Lett. 2006, 16, 5963-5967. (18) Benkovic, S. J.; Baker, S. J.; Alley, M. R. K.; Woo, Y.-H.; Zhang, Y.-K.; Akama, T.; Mao, W.; Baboval, J.; Rajagopalan, P. T. R.; Wall, M.; Kahng, L. S.; Tavassoli, A.; Shapiro, L. Identification of Borinic Esters as Inhibitors of Bacterial Cell Growth and Bacterial Methyltransferases, CcrM and MenH, J. Med. Chem. 2005, 48, 7468-7476. (19) Zhang, N.; Wang, C.; Zou, G.; Tang, J. Palladium-Catalyzed Cross-Coupling of Aryl Chlorides with O, N-Chelate Stabilized Diarylborinates, J. Organomet. Chem. 2017, 842, 54-58. (20) Dimitrijević, E.; Taylor, M. S. Organoboron Acids and Their Derivatives as Catalysts for Organic Synthesis, ACS Catal. 2013, 3, 945-962. (21) Taylor, M. S. Catalysis Based on Reversible Covalent Interactions of Organoboron Compounds, Acc. Chem. Res. 2015, 48, 295-305.


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(22) Lee, D.; Newman, S. G.; Taylor, M. S. Boron-Catalyzed Direct Aldol Reactions of Pyruvic Acids, Org. Lett. 2009, 11, 5486-5489. (23) El Dine, T. M.; Rouden, J.; Blanchet, J. Borinic Acid Catalysed Peptide Synthesis, Chem. Commun. 2015, 51, 16084-16087. Please see the correction by authors for the role of borinic acid: Chem. Commun., 2018, 54, 5142. (24) El Dine, T. M.; Evans, D.; Rouden, J.; Blanchet, J. Formamide Synthesis through Borinic Acid Catalysed Transamidation under Mild Conditions, Chem. Eur. J. 2016, 22, 58945898. (25) Chardon, A.; El Dine, T. M.; Legay, R.; De Paolis, M.; Rouden, J.; Blanchet, J. Borinic Acid Catalysed Reduction of Tertiary Amides with Hydrosilanes: A Mild and Chemoselective Synthesis of Amines, Chem. Eur. J. 2017, 23, 2005-2009. (26) Crossley, D. L.; Cid, J.; Curless, L. D.; Turner, M. L.; Ingleson, M. J. Facile Arylation of Four-Coordinate Boron Halides by Borenium Cation Mediated Boro-desilylation and destannylation, Organometallics 2015, 34, 5767-5774. (27) Crossley, D. L.; Cade, I. A.; Clark, E. R.; Escande, A.; Humphries, M. J.; King, S. M.; Vitorica-Yrezabal, I.; Ingleson, M. J.; Turner, M. L. Enhancing Electron Affinity and Tuning Band Gap in Donor-Acceptor Organic Semiconductors by Benzothiadiazole Directed C–H Borylation, Chem. Sci. 2015, 6, 5144-5151. (28) Sadu, V. S.; Bin, H.-R.; Lee, D.-M.; Lee, K.-I. One-pot synthesis of four-coordinate boron(III) complexes by the ligand-promoted organic group migration between boronic acids, Sci. Rep. 2017, 7, 242.


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(29) Povlock, T. P.; Lippincott, W. T. The Reaction of Trimethoxyboroxine with Aromatic Grignard Reagents: A New Synthesis of Borinic Acids, J. Am. Chem. Soc. 1958, 80, 5409-5411. (30) Chen, X.; Ke, H.; Chen, Y.; Guan, C.; Zou, G. Cross-Coupling of Diarylborinic Acids and Anhydrides with Arylhalides Catalyzed by a Phosphite/N-Heterocyclic Carbene Co-supported Palladium Catalyst System, J. Org. Chem. 2012, 77, 7572-7578. (31) Marciasini L, Cacciuttolo B, Vaultier M, Pucheault M, Synthesis of Borinic Acids and Borinate Adducts Using Diisopropylaminoborane, Org Lett. 2015, 17, 3532-3535. (32) Letsinger R. L.; Skoog, I. Organoboron Compounds. IV. Aminoethyl Diarylborinates, J. Am. Chem. Soc. 1955, 77, 2491-2494. (33) Hayashi, Y. Pot Economy and One-Pot Synthesis, Chem. Sci. 2016, 7, 866-880. (34) Tang, W.; Sarvestani, M.; Wei, X.; Nummy, L. J.; Patel, N.; Narayanan, B.; Byrne, D.; Lee, H.; Yee, N. K.; Senanayake, C. H. Formation of 2-Trifluoromethylphenyl Grignard Reagent via Magnesium-Halogen Exchange: Process Safety Evaluation and Concentration Effect, Org. Process Res. Dev. 2009, 13, 1426-1430, and references therein.


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TOC Graphic


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Development of a Telescoped Process for Preparation of N, O

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