Cyclization of Amino Acid

Subscriber access provided by READING UNIV

Article

RE[N(SiMe3)2]3-Catalyzed Guanylation/Cyclization of Amino Acid Esters and Carbodiimides Chengrong Lu, Chao Gong, Bei Zhao, Lijuan Hu, and Yingming Yao J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.7b02550 • Publication Date (Web): 16 Jan 2018 Downloaded from http://pubs.acs.org on January 16, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

The Journal of Organic Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 7 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

The Journal of Organic Chemistry

RE[N(SiMe3)2]3-Catalyzed Guanylation/Cyclization of Amino Acid Esters and Carbodiimides Chengrong Lu, Chao Gong, Bei Zhao*, Lijuan Hu, and Yingming Yao Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People’s Republic of China. Email: [email protected]

Supporting Information Placeholder

ABSTRACT: The example of rare-earth metal-catalyzed guanylation/cyclization of amino acid esters and carbodiimides is wellestablished, forming 4(3H)-2-alkylamino quinazolinones in 65-96% yields. The rare-earth metal amides RE[N(TMS)2]3 (RE = Y, Yb, Nd, Sm, La; TMS = SiMe3) showed high activities and La[N(TMS)2]3 performed best in a wide scope of the substrates.

Introduction N-Heterocyclic compounds quinazolinones are well noted for their wide existence among natural products and more importantly for their potent biological and medicinal properties.1 Efficient synthetic methods of quinazolinones and their derivatives have attracted much attention for several years. Treatment of 2-halobenzoic acid with guanidines2 yielded quinazolinones in the presence of copper iodide. The transformation found limited application due to the relative narrow substrate scope and a large dosage of additives. Palladium and molybdenum-mediated domino cyclocarbonylation/cyclizations were convenient methods for the synthesis of 2-aminoquinazolinones, which avoided using gaseous CO.3 However, low reactant diversity was the disadvantage in some cases. Aminolysis of isatoic anhydride, followed by reacting with cyanamide,4 isocyanide,5 or isothiocyanate,6 produces miscellaneous quinazolinones, which were I2/cumyl hydroperoxide-mediate or catalyzed by Cu, Pd, or Co complexes. Only one example was found to yield the target quinazolinones from isatoic anhydride without any catalyst.7 Utilizing the azaWittig reaction of iminophosphorane with heterocumulene on solid phase, for the synthesis of 2-amino-substituted 3Hquinazoline-4-one usually began with isatoic anhydride as well.8 Because of the commercially available or readily generated isatoic anhydride, which gave rise to differently substituted quinazolinone skeletons, the strategies based on isatoic anhydride were popular. However, the toxic reagents are usually required, and generally long and tedious procedures lead to unsatisfying overall yields in many cases. Recently, novel pathways have been explored to construct quinazolinones starting with amino acid ester and cyanamide, isothiocyanate, or thiourea.9 Xi and Zhang developed a Zn-catalyzed tandem guanylation/amidation of amino acid ester, in which car-

bodiimides was used instead.10 As we know, transition metal compounds especially rare-earth metal complexes with diverse ligands have excellent activities in the guanylation reaction.11 So it is a rational attempt to employ the rare-earth metal complex in the guanylation/cyclization of amino acid esters and carbodiimides. A series of 4(3H)-2-alkylamino quinazolinones in good to excellent yields were obtained using rare-earth metal amides RE[N(TMS)2]3 as the catalysts.

Results and discussion In many cases, the reactivity of rare-earth metal complexes is greatly influenced by ligand structure. The initial test was thus started from the screening of rare-earth metal catalysts, while the neat reaction of ethyl 2-aminobenzoate 1a with N,N’diisopropyl carbodiimide 2a (iPrN=C=NiPr, simplified as DIC) was examined as the model reaction. The results are summarized in Table 1. To our delight, all the rare-earth metal compounds we used, including trivalent ytterbium compounds YbCl3, Yb(OAr)3 (Ar = 2,6-tBu2C6H3), Yb[N(TMS)2]3, and Yb[N(TMS)2]3(µ-Cl)Li(THF)3 successfully catalyze the guanylation/cyclization of the model reaction in good yields (55-70%) (Table 1, entries 1-4). Overall consideration of the preparation procedure and the activities of the compounds, the simple trivalent ytterbium amide Yb[N(TMS)2]3 was chosen as the ideal catalyst. And the subsequent screening of reaction temperature based on the ytterbium amide suggested 60 oC was optimal (Table 1, entries 3, and 5-6). Rare earth metal amides of different metal centers were tested, which gave rise to yields of ~60% (Table 1, entries 3 and 7-10). Table 1 Screening of catalystsa

ACS Paragon Plus Environment

The Journal of Organic Chemistry 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

T (oC) Yield (%)b

Entry

Cat.

1

YbCl3 t

80

58

2

(2,6- Bu2C6H3O)3Yb

80

57

3

Yb[N(TMS)2]3

80

66

4

Yb[N(TMS)2]3(µ-Cl)Li(THF)3

80

55

5

Yb[N(TMS)2]3

40

52

6

Yb[N(TMS)2]3

60

67

7

La[N(TMS)2]3

60

61

8

Nd[N(TMS)2]3

60

68

9

Sm[N(TMS)2]3

60

59

10

Y[N(TMS)2]3

60

65

a b

Page 2 of 7

Conditions: 1 mmol of 2-aminobenzoates, 1 mmol of DIC. Isolated yields.

Since the yields stayed around 60% and a certain amount of reactant 1a was always observed by TLC detection after the reaction was quenched, while DIC was fully consumed, apparently some other reaction occurred to DIC. It was conjectured that ethanol released during the cyclization may consume the reactant DIC. To verify the hypothesis, the reaction of ethanol with DIC in 1:1 molar ratio was conducted in the presence of lanthanum amide La[N(TMS)2]3, and the byproduct isourea 4 was isolated in 75% yield (Scheme 1). Meanwhile, in CDCl3, the in situ 1H NMR spectrum of the model reaction (Figure 1(a)) catalyzed by La[N(TMS)2]3 was carried out for 24 h, which showed the main reaction occurred (Figure 1(b)), together with the addition of ethanol with DIC (Figure 1(c)), when the molar ratio of DIC 2a to ethyl 2aminobenzoate 1a was 2:1. Thus, molecular sieves and anhydrous calcium dichloride were deliberately added to remove ethanol in the catalytic system, respectively. However, the strategy had no significant effects on the outcomes of the experiments, for the yields of 3-isopropyl-2-(isopropylamino)quinazolin-4(3H)-one 3aa were still unsatisfying, varied from 56-66% (SI, Table S1). Nevertheless, when the molar ratio of 2a to 1a increased to 2:1, the yields of the product dramatically increased up to 96% (Table 2, entry 9). Thus, our hypothesis about the side reaction of ethanol addition to the carbodiimide was confirmed, and it happened to be reported by Tamm and Eisen recently, using actinide complexes as catalysts.12

Scheme 1 The addition reaction of ethanol with DIC

Figure 1 (a) In situ 1H NMR spectrum of the model reaction with the molar ratio of 2a to 1a 2: 1; (b) the 1H NMR spectrum of major product 3aa; (c) the 1H NMR spectrum of byproduct 4. Subsequently, a routine screening of the reaction conditions, including the central metals of rare-earth metal amides, catalyst loading, temperature, solvent, and reaction time was assessed with the 1:2 molar ratio of 1a to 2a. The results showed us that with the increasing of metal ion radius (Yb ~ Y< Gd < Sm < Nd < La), the yields of 4(3H)-2-isopropylamino quinazolinone 3aa increased from 40% to 84% (Table 2, entries 1-6). Raising the temperature is beneficial to the reaction (Table 2, entries 1 and 7-9), whereas the solvent has a negative effect on the reaction (Table 2, entries 9-12). Reaction time and the amount of catalyst cannot be reduced on the premise of ensuring the yield (Table 2, entries 9 and 13-17). As a result, the reaction should be performed better in the presence of 5 mol% La[N(TMS)2]3 at 100 oC for 24 h without solvent. Table 2 Screening of the optimal conditions a

Entry

Cat.

Catalyst Solvent loading (mol%)

1 2 3 4 5 6 7 8 9 10 11

La[N(TMS)2]3 Nd[N(TMS)2]3 Sm[N(TMS)2]3 Gd[N(TMS)2]3 Y[N(TMS)2]3 Yb[N(TMS)2]3 La[N(TMS)2]3 La[N(TMS)2]3 La[N(TMS)2]3 La[N(TMS)2]3 La[N(TMS)2]3

5 5 5 5 5 5 5 5 5 5 5

12 13

La[N(TMS)2]3 La[N(TMS)2]3

5 5

Toluene 1,4Dioxane DMSO -

T (oC)

Time Yield (h) (%)b

60 60 60 60 60 60 40 80 100 100 100

24 24 24 24 24 24 24 24 24 24 24

84 81 74 65 42 40 78 86 96 40 36

100 100

24 6

43 76

2 ACS Paragon Plus Environment

Page 3 of 7 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

The Journal of Organic Chemistry

14 15 16 17 a

La[N(TMS)2]3 La[N(TMS)2]3 La[N(TMS)2]3 La[N(TMS)2]3

5 5 2.5 1

-

100 100 100 100

12 18 24 24

80 85 55 20

An ester group effect of 2-aminobenzoates has also been studied. The esters bearing bulky leaving groups, such as tBu and n Bu, turned out to be outstanding substrates and the products 3aa were obtained in 94% and 93% (Table 3, entries 5 and 6). Consideration of the practicability, environmental friendliness and potential production cost, ethyl 2-aminobenzoates were still recommended.


b

The evaluation of the substrate scope under optimal conditions was summarized in Scheme 2. The electronic effect of the substituents of the esters has great effect on the outcomes. When using 5-substituted ethyl 2-aminobenzoates bearing electron-withdrawing groups (F-, Cl-, Br-, I-, pyridinyl), the stronger the electron withdrawing abilities of the groups were, the lower the yields were (Scheme 2, 3ba-3fa). Electron donating groups (OMe-, Me- and naphthyl) also lead to a slight drop in yields (Scheme 2, 3ga-3ja). Excellent yields of the products were obtained by using different carbodiimides, including symmetrical or unsymmetrical carbodiimides (Scheme 2, 3ab3ag’). It is worth mentioning that when using unsymmetrical carbodiimides with aromatic and aliphatic substituents in different side, meanwhile the aliphatic substituent in the form of NCH2R, a pair of cyclization isomers were obtained (Scheme 2, 3ad and 3ad’, 3ag and 3ag’). Compared with the reported spectra of the same compounds in previous work, 8c the major products were 3ad and 3ag, respectively. Furthermore, imino acid esters also gave out the corresponding product 3kb in 91% yield. Scheme 2 Substrate scope

O

O

N

NH

N

N

O

N

NH

3ea, 86%

N

N

O

O

3ia, 87%

N

3ja, 97%

O

N

N N

Ph NH Bn

3ad

65(32)%

O

N N

Bn N NH Ph

3ad'

N

3ag

N NH n Bu 66(31)%

N

3ag'

1 2 3 4 5 6

Me Et Bn i Pr n Bu t Bu

68 85 73 83 93 94

a


b

Based on the mechanism raised by Zhang10 and the evidence from the 1H NMR experiment mentioned above, we proposed the possible mechanism of the current transformation, shown in Scheme 3. The aminolysis of rare-earth metal amide RE[N(TMS)2]3 with ethyl 2-aminobenzoate would gernerate intermediate A. Coordination of carbodiimide DIC to A /intramolecular insertion might provide intermediate C. Intramolecular nucleophilic amidation in C should occur to release 3aa and yield intermediate D at the same time. Finally, intermediate D underwent proton exchange with another molecule of ethyl 2-aminobenzoate to regenerate the active species A, while a molecule of ethanol was released. The byproduct ethanol was captured by DIC to yield isourea 4 under the same condition. In the case of unsymmetrical carbodiimides, when forming intermediate B, it is tend to form the structure of B-1 rather than the structure B-2, since the electron cloud density of the N atom bearing the aromatic ring was somewhat greater than the other side, which leads to more powerful nucleophilic attack to the carbonyl carbon in the ester group (Scheme 4). N C N

Tol

N

NH Tol

N

N C

RE

RE[N(TMS)2]3

N

O HN(TMS)2

A

3ac, 95%

OEt

O

N

Ph EtOH

NH Cy

H N

RE B

N

NH t Bu

3af, 92%

N

N H

COOEt N RE

OEt

N

D

N Ph

OEt

O

DIC RE[N(TMS)2]3

4

NH2

Bu

NH Ph

H N

NH2

O

n

N

Yield(%)b

COOEt

N

Ph

3ae, 90%

O

R

O

O

Ph N

NH Ph

3ab, 98%

O

NH

3ha, 83%

Ph

N NH

N

Entry

O

N NH

N NH

3ga, 86%

N N

NH

NH

O N

3fa, 80%

O

N N

3da, 82%

O N

N

NH

3ca, 76%

O N

Br

N

NH

3ba, 66%

O

O

Cl

N

3aa, 96%

I

O

F

N

Table 3 The influence of different alkoxy groups of estersa

N RE O

N

OEt

O

Ph

C

3kb, 91%

N N 3aa


NH

3


Page 4 of 7

Ethyl 2-amino-5-chlorobenzoate (1c). 1H NMR (400 MHz, CDCl3): δ 7.83 (d, J = 2.5 Hz, 1H, ArH), 7.20 (dd, J = 8.8, 2.5 Hz, 1H, ArH), 6.60 (d, J = 8.8 Hz, 1H, ArH), 5.73 (s, 2H, NH2), 4.33 (q, J = 7.1 Hz, 2H, CH2), 1.39 (t, J = 7.1 Hz, 3H, CH3) ppm.

Scheme 3 Possible catalytic mechanism.

Ethyl 2-amino-5-bromobenzoate (1d). 1H NMR (400 MHz, CDCl3): δ 7.97 (d, J = 2.4 Hz, 1H, ArH), 7.32 (dd, J = 8.8, 2.4 Hz, 1H, ArH), 6.57 (t, J = 7.5 Hz, 1H, ArH), 5.76 (s, 2H, NH2), 4.33 (q, J = 7.1 Hz, 2H, CH2), 1.39 (t, J = 7.1 Hz, 3H, CH3) ppm.

Scheme 4 Possible intermediate.

Conclusion In summary, a rare-earth metal amide catalyzed guanylation/cyclization of amino acid esters and carbodiimides is an ideal method for the synthesis of 3-alkyl-4(3H)-2-alkylamino quinazolinones, which is the first utility of rare-earth metal complexes in this field. The readily available catalyst Ln[N(TMS)2]3 exhibits broad substituent tolerance, mild conditions, and provides 3-alkyl-4(3H)-2-alkylamino quinazolinones in good to excellent yields. The plausible mechanism of the guanylation/cyclization transformation is described in detail. Furthermore, a competitive reaction, the addition of alcohols with carbodiimides was observed in the process, which was also catalyzed by RE[N(TMS)2]3. Extensive studies are now in progress in our laboratory.

Experimental section

Ethyl 2-amino-5-iodobenzoate (1e). 1H NMR (400 MHz, CDCl3): δ 8.05 (d, J = 2.2 Hz, 1H, ArH), 7.38 (dd, J = 8.7, 2.2 Hz, 1H, ArH), 6.36 (d, J = 8.7 Hz, 1H, ArH), 5.69 (s, 2H, NH2), 4.24 (qd, J = 7.1, 3.4 Hz, 2H, CH2), 1.30 (t, J = 7.1 Hz, 3H, CH3) ppm. Ethyl 2-amino-5-methoxybenzoate (1g). 1H NMR (400 MHz, CDCl3): δ 7.36 (d, J = 3.0 Hz, 1H, ArH), 6.93 (dd, J = 8.9, 3.0 Hz, 1H, ArH), 6.61 (d, J = 8.9 Hz, 1H, ArH), 5.42 (s, 2H, NH2), 4.33 (q, J = 7.1 Hz, 2H, CH2), 3.75 (s, 3H, OCH3), 1.38 (t, J = 7.1 Hz, 3H, CH3) ppm. Ethyl 2-amino-5-methylbenzoate (1h). 1H NMR (400 MHz, CDCl3): δ 7.67 (s, 1H, ArH), 7.09 (dd, J = 8.3, 1.9 Hz, 1H, ArH), 6.59 (d, J = 8.3 Hz, 1H, ArH), 5.53 (s, 2H, NH), 4.33 (q, J = 7.1 Hz, 2H, CH2), 2.24 (s, 3H, ArCH3), 1.39 (t, J = 7.1 Hz, 3H, CH3) ppm. Ethyl 3-amino-2-naphthoate (1i). 1H NMR (400 MHz, CDCl3): δ 8.50 (s, 1H, ArH), 7.72 (d, J = 8.3 Hz, 1H, ArH), 7.53 (d, J = 8.3 Hz, 1H, ArH), 7.46 – 7.34 (m, 1H, ArH), 7.23 – 7.13 (m, 1H, ArH), 6.97 (s, 1H, ArH), 5.58 (s, 2H, NH2), 4.42 (q, J = 7.1 Hz, 2H, CH2), 1.45 (t, J = 7.1 Hz, 3H, CH3) ppm.

General Procedures. All manipulations and reactions were conducted under a purified argon atmosphere using standard Schlenk or glovebox techniques. Solvents were degassed and distilled from sodium benzophenone ketyl under argon prior to use. All commercial available chemicals, including liquid amino acid esters and carbodiimides, were dried with CaH2 and distilled in a vacuum or at atmospheric pressure prior to use. Amino acid esters, other than 1a, 1f, 1j and 1k (bought from J&K Chemical), were prepared. Unsymmetrical carbodiimides 2b-2g were synthesized following the previous work.13 Rare-earth metal catalysts YbCl3,14 (2,6t Bu2C6H3ArO)3Yb,15 Yb[N(TMS)2]3,16 and Yb[N(TMS)2]3(µCl)Li(THF)3 17 were prepared according to literature methods, respectively. NMR spectra were recorded using a Bruker-400 MHz spectrometer at room temperature. High Resolution Mass (HRMS) spectra were obtained using Bruker ESI-TOF.

In a typical procedure, corresponding isothiocyanates and amines were ground manually in a mortar in a 1:1 stoichiometric ratio for 15-20 minutes. After that, the solid product was scraped off the walls of the mortar affording thiourea quantitatively. To a solution of iodine (20.0 mmol) and triphenylphosphine (20 mmol) in CH2Cl2 (80 mL), a solution of 16.7 mmol thiourea and triethylamine (41.4 mmol) in CH2Cl2 (80 mL) was added and the mixture was stirred under ultrasonic. According to the TLC test, the reaction was quenched after appropriate time. The crude mixture was concentrated under reduced pressure, then purified by column chromatography using hexane as the elution to give the carbodiimide.

Typical procedure for the preparation of amino acid esters:

Characteristic data of carbodiimides:

Thionyl chloride (23.52 mmol) was added dropwise to a solution of 2-amino-5-chlorobenzoic acid (19.6 mmol) in 50 mL ethanol in ice bath. The mixture was heated to reflux for 18 h, then neutralized by adding saturated aqueous NaHCO3. The mixture was extracted with ethyl acetate for three times, the organic layer was collected and dried over anhydrous Na2SO4, filtered. After solvent evaporation under reduced pressure, the crude mixture was purified by flash column chromatography to give the product 1c as a pale-yellow solid (1.6 g, 70 %). Characteristic data of amino acid esters: 1

Ethyl 2-amino-5-fluorobenzoate (1b). H NMR (400 MHz, CDCl3): δ 7.54 (dd, J = 9.7, 3.1 Hz, 1H, ArH), 7.01 (ddd, J = 9.0, 7.7, 3.1 Hz, 1H, ArH), 6.60 (dd, J = 9.0, 4.5 Hz, 1H, ArH), 5.58 (s, 2H, NH2), 4.32 (q, J = 7.1 Hz, 2H, CH2), 1.37 (t, J = 7.1 Hz, 3H, CH3) ppm.

Typical procedure for the preparation of carbodiimides

Diphenylmethanediimine (2b). 1H NMR (400 MHz, CDCl3): δ 7.42- 7.30 (m, 4H, ArH), 7.27-7.17 (m, 6H, ArH) ppm. Di-p-tolylmethanediimine (2c). 1H NMR (400 MHz, CDCl3): δ 7.12 (dd, J = 20.7, 8.2 Hz, 8H, ArH), 2.35 (s, 6H, CH3) ppm. N-Benzyl-N-phenylmethanediimine (2d). 1H NMR (400 MHz, CDCl3): δ 7.37 (d, J = 4.4 Hz, 4H, ArH), 7.30 (dt, J = 8.8, 4.3 Hz, 1H, ArH), 7.24 (t, J = 7.8 Hz, 2H, ArH), 7.09 (t, J = 7.4 Hz, 1H, ArH), 6.99 (d, J = 7.5 Hz, 2H, ArH), 4.56 (s, 2H, CH2) ppm. N-Cyclohexyl-N-phenylmethanediimine (2e). 1H NMR (400 MHz, CDCl3): δ 7.33 – 7.18 (m, 2H, ArH), 7.16 – 7.03 (m, 3H, ArH), 3.56 – 3.34 (m, 1H, CH), 2.07 – 1.90 (m, 2H, CH2), 1.82 – 1.70 (m, 2H, CH2), 1.61 – 1.41 (m, 3H, CH2), 1.40 – 1.21 (m, 3H, CH2) ppm.


4

Page 5 of 7 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

The Journal of Organic Chemistry N-tert-Butyl-N-phenylmethanediimine (2f). 1H NMR (400 MHz, CDCl3): δ 7.31 – 7.22 (m, 2H, ArH), 7.15 – 7.04 (m, 3H, ArH), 1.39 (s, 9H, CH3) ppm. N-Butyl-N-phenylmethanediimine (2g). 1H NMR (400 MHz, CDCl3): δ 7.39 – 7.18 (m, 2H, ArH), 7.12 – 7.00 (m, 3H, ArH), 3.40 (t, J = 6.8 Hz, 2H, CH2), 1.78 – 1.54 (m, 2H, CH2), 1.51 – 1.33 (m, 2H, CH2), 0.94 (t, J = 7.4 Hz, 3H, CH3) ppm. Typical procedure for the guanylation/cyclization of amino acid esters and carbodiimides A 5 mL Schlenk tube under dried argon was charged with Yb[N(TMS)2]3 (0.05 mmol), ethyl 2-aminobenzoate (1.00 mmol) and a stirring bar. After the catalyst was dissolved, DIC (2.00 mmol) was added into the tube. The mixture was stirred at 100 oC for 24 h, diluted with ethyl acetate, and then the crude mixture was purified by column chromatography with ethyl acetate/ petroleum ether (1:20) to give the desired product as a colorless solid. Characteristic data of quinazolin-4(3H)-ones: 3-Isopropyl-2-(isopropylamino)quinazolin-4(3H)-one (3aa). Colorless solid, Yield: 96 %; 1H NMR (400 MHz, CDCl3): δ 8.08 (dd, J = 8.0, 1.3 Hz, 1H, ArH), 7.59 – 7.48 (m, 1H, ArH), 7.31 (d, J = 8.1 Hz, 1H, ArH), 7.16 – 7.01 (m, 1H, ArH), 5.48 (s, 1H, NH), 4.40 (dd, J = 11.2, 5.1 Hz, 2H, CH), 1.55 (d, J = 7.2 Hz, 6H, CH3), 1.31 (d, J = 6.2 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 163.4, 149.2, 149.1, 134.2, 127.3, 124.7, 122.4, 117.7, 43.8, 23.1, 20.5 ppm. HRMS (ESI-TOF) m/z: [M+Na]+ calcd for C14H19N3ONa 268.1420; Found 268.1435. M.p.: 79.8-80.1 oC. 6-Fluoro-3-isopropyl-2-(isopropylamino)quinazolin-4(3H)-one (3ba). Colorless solid, Yield: 66 %; 1H NMR (400 MHz, CDCl3): δ 7.61 (dd, J = 8.8, 2.8 Hz, 1H, ArH), 7.29 – 7.06 (m, 2H, ArH), 5.30 (s, 1H, NH), 4.36 (d, J = 6.8 Hz, 1H, CH), 4.26 (dq, J = 13.1, 6.5 Hz, 1H, CH), 1.46 (d, J = 7.2 Hz, 6H, CH3), 1.21 (d, J = 6.4 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 162.7, 162.6, 159.4, 157.0, 148.6, 145.8, 126.7, 126.6, 122.7, 122.4, 118.2, 118.1, 111.6, 111.3, 43.8, 22.9, 20.2 ppm. 19F NMR (376.5 MHz, CDCl3): δ -120.07 ppm. HRMS (ESI-TOF) m/z: [M+H]+calcd for C14H19FN3O 264.1507; Found 264.1499. M.p.: 80.9-81.6 oC. 6-Chloro-3-isopropyl-2-(isopropylamino)quinazolin-4(3H)one (3ca). Colorless solid, Yield: 76 %; 1H NMR (400 MHz, CDCl3): δ 8.03 (d, J = 2.4 Hz, 1H, ArH), 7.46 (dd, J = 8.7, 2.5 Hz, 1H, ArH), 7.30 – 7.20 (m, 1H, ArH), 5.43 (s, 1H, NH), 4.51 – 4.29 (m, 2H, CH), 1.55 (d, J = 7.2 Hz, 6H, CH3), 1.31 (d, J = 6.2 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 162.4, 149.2, 147.8, 134.5, 127.5, 126.5, 126.4, 118.6, 43.9, 23.1, 20.4 ppm. HRMS (ESI-TOF) m/z: [M+Na]+ calcd for C14H18ClN3ONa 302.1031; Found 302.1028. M.p.: 119.4-120.8 oC. 6-Bromo-3-isopropyl-2-(isopropylamino)quinazolin-4(3H)-one (3da). Colorless solid, Yield: 82 %; 1H NMR (400 MHz, CDCl3): δ 8.18 (d, J = 2.1 Hz, 1H, ArH), 7.58 (dd, J = 8.7, 2.3 Hz, 1H, ArH), 7.18 (d, J = 8.7 Hz, 1H, ArH), 5.43 (s, 1H, NH), 4.51 – 4.26 (m, 2H, CH), 1.54 (d, J = 7.2 Hz, 6H, CH3), 1.30 (d, J = 6.3 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 162.2, 149.3, 148.1, 137.2, 129.6, 126.7, 119.1, 114.8, 43.9, 23.0, 20.4 ppm. HRMS (ESI-TOF) m/z: [M+Na]+ calcd for C14H18BrN3ONa 346.0525; Found 346.0541. M.p.: 129.5-130.8 oC. 6-Iodo-3-isopropyl-2-(isopropylamino)quinazolin-4(3H)-one (3ea). Colorless solid, Yield: 86 %; 1H NMR (400 MHz, CDCl3): δ 8.36 (d, J = 2.1 Hz, 1H, ArH), 7.73 (dd, J = 8.6, 2.2 Hz, 1H, ArH), 7.04 (d, J = 8.6 Hz, 1H, ArH), 5.38 (s, 1H, NH), 4.47 (d, J = 6.7 Hz, 1H, CH), 4.35 (dq, J = 13.1, 6.5 Hz, 1H, CH), 1.52 (d, J

= 7.2 Hz, 6H, CH3), 1.28 (d, J = 6.4 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 162.0, 149.3, 148.6, 142.6, 135.8, 126.9, 119.6, 84.7, 43.9, 23.0, 20.3 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C14H19IN3O 372.0567; Found 372.0558. M.p.: 120.5-121.7 oC. 3-Isopropyl-2-(isopropylamino)pyrido[2,3-d]pyrimidin-4(3H)one (3fa). Colorless solid, Yied: 80 %; 1H NMR (400 MHz, CDCl3): δ 8.69 (dd, J = 4.6, 2.1 Hz, 1H, ArH), 8.35 (dd, J = 7.8, 2.1 Hz, 1H, ArH), 7.04 (dd, J = 7.8, 4.6 Hz, 1H, ArH), 5.41 (s, 1H, NH), 4.68 (d, J = 6.6 Hz, 1H, CH), 4.63 – 4.52 (m, 1H, CH), 1.54 (d, J = 7.2 Hz, 6H, CH3), 1.31 (d, J = 6.5 Hz, 6H, CH3) ppm. 13 C NMR (100 MHz, CDCl3): δ 163.5, 159.0, 156.0, 151.3, 136.9, 118.3, 112.3, 44.1, 23.1, 20.4 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C13H19N4O 247.1553; Found 247.1545. M.p.: 185.9-187.1 oC. 3-Isopropyl-2-(isopropylamino)-6-methoxyquinazolin-4(3H)one (3ga). Colorless solid, Yield: 86 %; 1H NMR (400 MHz, CDCl3): δ 7.42 (d, J = 2.9 Hz, 1H, ArH), 7.25 – 7.17 (m, 1H, ArH), 7.11 (dd, J = 8.9, 3.0 Hz, 1H, ArH), 5.38 (s, 1H, NH), 4.27 (dq, J = 12.9, 6.5 Hz, 1H, CH), 4.22 – 4.13 (m, 1H, CH), 3.78 (s, 3H, OCH3), 1.49 (d, J = 7.2 Hz, 6H, CH3), 1.23 (d, J = 6.4 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 163.3, 155.4, 148.0, 143.9, 126.4, 124.8, 117.9, 106.6, 55.9, 43.8, 23.1, 20.5 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C15H22N3O2 276.1707; Found 276.1700. M.p.: 123.9-124.8 oC. 3-Isopropyl-2-(isopropylamino)-6-methylquinazolin-4(3H)one (3ha). Colorless solid, Yield: 83 %; 1H NMR (400 MHz, CDCl3): δ 7.88 (s, 1H, ArH), 7.37 (dd, J = 8.3, 1.9 Hz, 1H, ArH), 7.29 – 7.19 (m, 1H, ArH), 5.48 (s, 1H, NH), 4.48 – 4.23 (m, 2H, CH), 2.38 (s, 3H, ArCH3), 1.55 (d, J = 7.2 Hz, 6H, CH3), 1.31 (d, J = 6.3 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 163.4, 148.7, 147.1, 135.7, 132.1, 126.6, 124.6, 117.5, 43.8, 23.1, 21.1, 20.5 ppm. HRMS (ESI-TOF) m/z: [M+Na]+ calcd for C15H21N3ONa 282.1577; Found 282.1591. M.p.: 134.8-136.3 oC. 3-Isopropyl-2-(isopropylamino)benzoquinazolin-4(3H)-one (3ia). Yellow solid, Yield: 87 %; 1H NMR (400 MHz, CDCl3): δ8.63 (s, 1H, ArH), 7.83 (d, J = 8.3 Hz, 1H, ArH), 7.72 (d, J = 8.4 Hz, 1H, ArH), 7.67 (s, 1H, ArH), 7.41 – 7.35 (m, 1H, ArH), 7.25 (t, J = 7.2 Hz, 1H, ArH), 5.38 (s, 1H, NH), 4.48 – 4.21 (m, 2H, CH), 1.50 (d, J = 7.2 Hz, 6H, CH3), 1.26 (d, J = 6.2 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 163.8, 148.2, 144.5, 137.6, 129.6, 129.5, 128.7, 128.0, 127.2, 124.3, 120.4, 118.6, 43.8, 23.1, 20.7 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C18H22N3O 296.1757; Found 296.1750. M.p.: 134.6-136.1 oC. 3-Isopropyl-2-(isopropylamino)-8-methylquinazolin-4(3H)one (3ja). Yellow solid, Yield: 97 %; 1H NMR (400 MHz, CDCl3): δ7.87 (dd, J = 8.0, 0.7 Hz, 1H, ArH), 7.34 (d, J = 7.1 Hz, 1H, ArH), 6.96 (t, J = 7.6 Hz, 1H, ArH), 5.36 (s, 1H, NH), 4.30 (dq, J = 12.9, 6.4 Hz, 2H, CH), 2.39 (s, 3H, CH3), 1.48 (d, J = 7.2 Hz, 6H, CH3), 1.27 (d, J = 6.4 Hz, 6H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 163.6, 148.1, 134.2, 132.7, 124.6, 121.8, 117.3, 44.0, 22.6, 20.2, 17.1 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C15H21N3O 260.1757; Found 260.1754. M.p.: 127.2-128.2 oC. 3-Phenyl-2-(phenylamino)quinazolin-4(3H)-one (3ab). Colorless solid, Yield: 98 %; 1H NMR (400 MHz, CDCl3): δ 8.15 (dd, J = 7.9, 1.0 Hz, 1H, ArH), 7.68 – 7.55 (m, 4H, ArH), 7.53 – 7.45 (m, 3H, ArH), 7.42 – 7.35 (m, 2H, ArH), 7.28 (t, J = 7.9 Hz, 2H, ArH), 7.25 – 7.19 (m, 1H, ArH), 7.06 (t, J = 7.4 Hz, 1H, ArH), 5.95 (s, 1H, NH) ppm. 13C NMR (100 MHz, CDCl3): δ 162.5, 148.6, 146.4, 137.9, 134.8, 134.6, 130.9, 130.3, 129.1,


5


129.0, 127.2, 125.7, 124.1, 123.7, 120.9, 118.5 ppm. HRMS (ESITOF) m/z: [M+Na]+ calcd for C20H15N3ONa 336.1107; Found 336.1125. M.p.: 140.0-141.4 oC.

125.1, 122.7, 117.8, 41.7, 31.5, 20.19, 14.0 ppm. HRMS (ESITOF) m/z: [M+H]+ calcd for C18H20N3O 294.1601; Found 294.1606. M.p.: 137.6-138.9 oC

3-(p-Tolyl)-2-(p-tolylamino)quinazolin-4(3H)-one (3ac). Colorless solid, Yield: 95 %; 1H NMR (400 MHz, CDCl3): δ 8.04 (dd, J = 7.9, 1.0 Hz, 1H, ArH), 7.56 – 7.45 (m, 1H, ArH), 7.37 (d, J = 8.1 Hz, 1H, ArH), 7.27 (dd, J = 8.1, 3.9 Hz, 4H, ArH), 7.17 – 7.06 (m, 3H, ArH), 6.98 (d, J = 8.2 Hz, 2H, ArH), 5.86 (s, 1H, NH), 2.33 (s, 3H, CH3), 2.19 (s, 3H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 162.7, 148.7, 146.8, 140.4, 135.3, 134.6, 133.7, 131.8, 131.5, 129.4, 128.7, 127.2, 125.6, 123.4, 121.2, 118.4, 21.4, 20.9 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C22H20N3O 342.1601; Found 342.1592. M.p.: 145.4-146.8 oC.

3-Butyl-2-(phenylamino)quinazolin-4(3H)-one (3ag’). Colorless liquid, Yield: 31 %; 1H NMR (400 MHz, CDCl3): δ 8.04 (dd, J = 8.0, 1.0 Hz, 1H, ArH), 7.46 (t, J = 7.4 Hz, 1H, ArH), 7.40 – 7.21 (m, 4H, ArH), 7.16 – 7.00 (m, 3H, ArH), 4.21 – 4.07 (m, 2H, CH2), 1.81 – 1.60 (m, 2H, CH2), 1.45 – 1.34 (m, 2H, CH2), 0.92 (t, J = 7.3 Hz, 3H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 162.4, 134.5, 129.6, 127.7, 124.1, 123.4, 122.0, 41.6, 30.1, 20.5, 14.0 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C18H20N3O 294.1601; Found 294.1608.

2-(Benzylamino)-3-phenylquinazolin-4(3H)-one (3ad). Colorless solid, Yield: 65 %; 1H NMR (400 MHz, CDCl3): δ 8.11 (d, J = 7.8 Hz, 1H, ArH), 7.58 (t, J = 7.6 Hz, 1H, ArH), 7.51 (t, J = 7.4 Hz, 2H, ArH), 7.44 (t, J = 7.6 Hz, 2H, ArH), 7.31 – 7.24 (m, 4H, ArH), 7.22 (d, J = 6.9 Hz, 3H, ArH), 7.15 (t, J = 7.5 Hz, 1H, ArH), 4.63 (d, J = 5.5 Hz, 2H, CH2), 4.43 (s, 1H, NH) ppm. 13C NMR (100 MHz, CDCl3): δ 162.7, 149.5, 149.4, 138.5, 134.7, 130.7, 130.0, 128.9, 128.7, 127.5, 127.4, 127.3, 125.1, 122.8, 117.8 ppm. HRMS (ESI-TOF) m/z: [M+Na]+ calcd for C21H17N3ONa 350.1264; Found 350.1279. M.p.: 136.3-137.7 oC. 3-Benzyl-2-(phenylamino)quinazolin-4(3H)-one (3ad’). Colorless solid, Yield: 32 %; 1H NMR (400 MHz, DMSO-d6): δ 8.69 (s, 1H, NH), 8.03 (dd, J = 7.9, 1.1 Hz, 1H, ArH), 7.69 – 7.62 (m, 1H, ArH), 7.57 (d, J = 7.7 Hz, 2H, ArH), 7.32 (td, J = 7.8, 4.0 Hz, 6H, ArH), 7.28 – 7.21 (m, 3H, ArH), 7.07 (t, J = 7.3 Hz, 1H, ArH), 5.61 (s, 2H, CH2) ppm. 13C NMR (100 MHz, DMSO-d6): δ 162.0, 148.2, 147.9, 139.1, 136.4, 134.5, 128.6, 128.4, 127.2, 126.7, 126.5, 123.5, 122.5, 117.2 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C21H17N3OH 328.1444; Found 328.1434. M.p.: 176.8-178.3 oC.

2-Phenyl-3-(phenylimino)hexahydroimidazo[1,5-a]pyridin1(5H)-one (3kb). Colorless solid, Yield: 91 %; 1H NMR (400 MHz, CDCl3): δ 7.32 (d, J = 7.1 Hz, 3H, ArH), 7.25 (d, J = 5.4 Hz, 2H, ArH), 7.10 (t, J = 7.4 Hz, 2H, ArH), 6.84 (t, J = 7.2 Hz, 1H, ArH), 6.76 (d, J = 7.5 Hz, 2H, ArH), 3.88 (dd, J = 11.4, 3.5 Hz, 1H, CH2), 3.72 – 3.47 (m, 1H, CH2), 2.69 (t, J = 12.4 Hz, 1H, CH), 2.24 (d, J = 12.9 Hz, 1H, CH2), 1.95 (d, J = 10.6 Hz, 1H, CH2), 1.58 – 1.40 (m, 3H, CH2), 1.29 – 1.22 (m, 1H, CH2) ppm. 13 C NMR (100 MHz, CDCl3): δ 147.7, 143.7, 133.1, 128.9, 128.7, 128.1, 127.8, 121.9, 121.8, 59.3, 43.0, 28.4, 25.0, 23.0 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C19H20N3O 306.1601; Found 306.1605. M.p.: 131.8-132.3 oC.

Characteristic data of isourea 4: Ethyl -N,N'-diisopropylcarbamimidate (4). Colorless oil, Yield: 60%; 1H NMR (400 MHz, CDCl3): δ 4.03 (q, J = 7.0 Hz, 2H, CH2), 3.73 (br, 1H, CH), 3.37 (br, 1H, NH), 3.12 (br, 1H, CH), 1.20 (t, J = 8.2 Hz, 3H, CH2CH3), 1.07 (s, 12H, CH(CH3)2) ppm. 13 C NMR (100 MHz, CDCl3): δ 150.9, 59.7, 45.1, 42.4, 23.2, 22.9, 13.4 ppm.

ASSOCIATED CONTENT 2-(Cyclohexylamino)-3-phenylquinazolin-4(3H)-one (3ae). Colorless solid, Yield: 90 %; 1H NMR (400 MHz, CDCl3): δ 8.12 (dd, J = 7.9, 1.1 Hz, 1H, ArH), 7.60 (dd, J = 11.6, 4.7 Hz, 3H, ArH), 7.53 (t, J = 7.3 Hz, 1H, ArH), 7.42 (d, J = 8.2 Hz, 1H, ArH), 7.30 (d, J = 7.3 Hz, 2H, ArH), 7.15 (t, J = 7.5 Hz, 1H, ArH), 4.07 – 3.96 (m, 1H, CH), 3.89 (d, J = 7.6 Hz, 1H, NH), 2.11 – 1.85 (m, 2H, CH2), 1.57 (d, J = 9.6 Hz, 3H, CH2), 1.49 – 1.31 (m, 2H, CH2), 1.20 – 1.11 (m, 1H, CH2), 1.11 – 0.94 (m, 2H, CH2) ppm. 13C NMR (100 MHz, CDCl3): δ 162.9, 149.9, 148.9, 135.0, 134.7, 130.7, 130.0, 129.0, 127.4, 125.1, 122.5, 117.7, 50.0, 33.0, 25.7, 24.7 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C20H22N3O 320.1757; Found 320.1762. M.p.: 121.1-122.2 oC. 2-(tert-Butylamino)-3-phenylquinazolin-4(3H)-one (3af). Colorless solid, Yield: 92 %; 1H NMR (400 MHz, CDCl3): δ 8.18 (d, J = 7.9 Hz, 1H, ArH), 7.69 – 7.61 (m, 3H, ArH), 7.58 (t, J = 7.4 Hz, 1H, ArH), 7.49 (d, J = 8.2 Hz, 1H, ArH), 7.37 – 7.30 (m, 2H, ArH), 7.21 (t, J = 7.5 Hz, 1H, ArH), 3.96 (s, 1H, NH), 1.45 (s, 9H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 163.0, 149.5, 148.2, 135.4, 134.6, 130.7, 129.9, 129.0, 127.3, 125.4, 122.5, 117.7, 52.6, 29.2 ppm. HRMS (ESI-TOF) m/z: [M+H]+ calcd for C18H20N3O 294.1601; Found 294.1602. M.p.: 148.0-149.0 oC. 2-(Butylamino)-3-phenylquinazolin-4(3H)-one (3ag). Colorless solid, Yield: 66 %; 1H NMR (400 MHz, CDCl3): δ 8.12 (dd, J = 7.9, 1.2 Hz, 1H, ArH), 7.67 – 7.50 (m, 4H, ArH), 7.43 (d, J = 8.2 Hz, 1H, ArH), 7.35 – 7.27 (m, 2H, ArH), 7.16 (t, J = 7.1 Hz, 1H, ArH), 3.99 (s, 1H, NH), 3.43 (dd, J = 12.6, 7.1 Hz, 2H, NHCH2), 1.48 (dt, J = 14.9, 7.4 Hz, 2H, CH2), 1.27 (dd, J = 15.1, 7.4 Hz, 2H, CH2), 0.89 (t, J = 7.3 Hz, 3H, CH3) ppm. 13C NMR (100 MHz, CDCl3): δ 162.9, 149.8, 135.0, 134.8, 130.8, 129.1, 127.4,

Supporting Information The Supporting Information is available free of charge on the ACS Publications website. Table S1, and 1H NMR and 13C NMR spectra of compounds 3aa-3ia and 4  

AUTHOR INFORMATION Corresponding Author * Fax: +86-512-65880305; Tel: +86-512-65880305.

ACKNOWLEDGMENT We gratefully acknowledge financial support from the National Natural Science Foundation of China (Grant No. 21572151) and PAPD.

REFERENCES [1] For selected reviews, see: (a) Gulevich, A. V.; Dudnik, A. S.; Chernyak, N.; Gevorgyan, V. Chem. Rev. 2013, 113, 3084; (b) Majumdar, K. C.; Debnath, P.; De, N.; Roy, B. Curr. Org. Chem. 2011, 15, 1760; (c) Davies, P. W.; Garzon, M. Asian J. Org. Chem. 2015, 4, 694. [2] Huang, X.; Yang, H.; Fu, H.; Qiao, R.; Zhao, Y. Synthesis 2009, 16, 2679. [3] (a) Roberts, B.; Liptrot, D.; Luker, T.; Stocks, M. J.; Barber, C.; Webb, N.; Dods, R.; Martin, B. Tetrahedron Lett. 2011, 52, 3793; (b) Åkerbladh, L.; Odell, L. R. J. Org. Chem. 2016, 81,6


Page 6 of 7

Page 7 of 7 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

The Journal of Organic Chemistry 2966. [4] Murthy, V. N.; Nikumbh, S. P.; Kumar, S. P.; Rao, L. V.; Raghunadh, A. Tetrahedron Lett. 2015, 56, 5767.

[17] Sheng, E.; Wang, S.; Yang, G.; Zhou, S.; Cheng, L.; Zhang, K.; Huang, Z. Organometallics 2003, 22, 684.

[5] (a) Ji, F.; Lv, M. Yi, W.; Cai, C. Org. Biomol. Chem. 2014, 12, 5766; (b) Vidyacharan, S.; Chaitra, N. C.; Sagar, A.; Sharada, D. S. Synth. Commun. 2015, 45, 898; (c) Ahmadi, F.; Bazgir, A. RSC Adv. 2016, 6, 61955; (d) Wei, T.; Xu, P.; Wang, S.; Ji, S. Eur. J. Org. Chem. 2016, 5393.; (e) Mirza, B. Tetrahedron Lett. 2016, 57, 146. [6] Mahdavi, M.; Asadi, M.; Khoshbakht. M.; Saeedi. M.; Bayat, M.; Foroumadi, A.; Shafiee, A. Helv. Chim. Acta 2016, 99, 378. [7] Asadi, M.; Ebrahimi, M.; Mahdavi, M.; Saeedi, M.; Ranjbar, P. R.; Yazdani, F.; Shafiee, Abbas.; Foroumadi, A. Synth. Commun. 2013, 43, 2385. [8] (a) Gopalsamy, A.; Yang, H. J. Comb. Chem. 2000, 2, 378; (b) Zhang, W.; Mayer, J. P.; Hall, S. E.; Weigel, J. A. J. Comb. Chem. 2001, 3, 255; (c) Liang, Y.; Ding, M.-W.; Liu, Z.-J.; Liu, X.-P. Synth. Commun. 2003, 33, 2843; (d) Xie, C.; Huang, N.; Ding, M. ARKIVOC 2009, 220; (e) Yang, X. H.; Wang, X.; Wu, M. H. Chin. J. Org. Chem. 2014, 34, 1015. [9] (a) Zeghida, W.; Debray, J.; Chierici, S.; Dumy, P.; Demeunynck, M. J. Org. Chem. 2008, 73, 2473; (b) Shestakov, A. S.; Bushmarinov, I. S.; Sidorenko, O. E.; Potapov, A. Y.; Shikhaliev, K. S.; Antipin, M. Y. Chem. Heterocyclic Comp. 2011, 47, 316; (c) Lecoutey, C.; Fossey, C.; Rault, S.; Fabis, F. Eur. J. Org. Chem. 2011, 2785; (d) Li, J.; Mi, Y.; He, J.; Luo, X.; Fan, E. J. Heterocyclic Chem. 2013, 50, 304. [10] Chi, Y.; Xu, L.; Du, S.; Yan, H.; Zhang, W.; Xi, Z. Chem. Eur. J. 2015, 21, 10369. [11] (a) Li, Q.; Wang, S.; Zhou, S.; Yang, G.; Zhu, X.; Liu, Y. J. Org. Chem. 2007, 72, 6763; (b) Zhang, W.; Nishiura, M.; Hou, Z. Chem. - Eur. J., 2007, 13, 4037; (c) Zhang, W.; Hou, Z. Org. Biomol. Chem. 2008, 6, 1720; (d) Du, Z.; Li, W.; Zhu, X.; Xu, F.; Shen, Q. J. Org. Chem. 2008, 73, 8966; (e) Han, F.; Teng, Q.; Zhang, Y.; Wang, Y.; Shen, Q. Inorg. Chem. 2011, 50, 2634; (f) Tu, J.; Li, W.; Xue, M.; Zhang, Y.; Shen, Q. Dalton Trans. 2013, 42, 5890; (g) Zhang, W.; Xu, L.; Xi, Z. Chem. Commun. 2015, 51, 254; (h) Xu, L.; Zhang, W.; Xi, Z. Organometallics 2015, 34, 1787; (i) Cheng, H.; Xiao, Y.; Lu, C.; Zhao, B.; Wang, Y.; Yao, Y. New J. Chem. 2015, 39, 7667; (j) Zhao, B.; Xiao, Y.; Yuan, D.; Lu, C.; Yao, Y. Dalton Trans. 2016, 45, 3880; (k) Gong, C.; Ding, H.; Lu, C.; Yao, Y.; Zhao, B. Dalton Trans. 2017, 46, 6031. [12] (a) Batrice, R. J.; Kefalidis, C. E.; Maron, L.; Eisen, M. S. J. Am. Chem. Soc. 2016, 138, 2114; (b) Liu, H.; Khononov, M.; Fridman, N.; Tamm, M.; Eisen, M, S. Inorg. Chem. 2017, 56, 3153; (c) Ghatak, T.; Fridman, N.; Eisen, M, S. Organometallics 2017, 36, 1296; (d) Liu, H.; Fridman, N.; Tamm, M.; Eisen, M. S. Organometallics 2017, 36, 4600; (e) Liu, H.; Fridman, N.; Tamm, M.; Eisen, M. S. Organometallics 2017, 36, 3896. [13] Duangkamol, C.; Pattarawarapan, M.; Phakhodee, W. Monatsh. Chem. 2016, 147, 1945. [14] Taylor, M. D.; Carter, C. P. J. Inorg. Nucl. Chem. 1966, 24, 387. [15] Zhang, L.; Yao, Y.; Luo, Y.; Shen, Q.; Sun, J. Polyhedron 2000, 19, 2243. [16] Bradley, D. C.; Ghotra, J. S.; Hart, F. A.; J .Chem. Soc., Dalton Trans. 1973, 1021.


7

Cyclization of Amino Acid

Recommend Documents