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Synlett 2007(2): 0255-0258  
DOI: 10.1055/s-2007-968024
LETTER
© Georg Thieme Verlag Stuttgart · New York

Naturally Occurring α-Amino Acid Catalyzed Coupling of Carbon Dioxide with Epoxides to Afford Cyclic Carbonates

Chaorong Qi, Huanfeng Jiang*, Zhaoyang Wang, Bo Zou, Shaorong Yang
Center of Green Chemistry, College of Chemistry, South China University of Technology, Guangzhou 510640, P. R. of China
Fax: +86(20)87112906; e-Mail: jianghf@scut.edu.cn;
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Publication History

Received 7 July 2006
Publication Date:
24 January 2007 (online)

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Abstract

A new and simple method was developed by using the naturally occurring α-amino acids as catalyst for the efficient coupling of carbon dioxide with epoxides to afford the corresponding cyclic carbonates. The cooperation of the ammonium group of one amino acid and the carboxylate ion of another one were proposed as a key activation factor for this transformation.

Key words

amino acids - epoxides - carbon dioxide - coupling reaction - cyclic carbonates

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Typical Experimental Procedure: Propylene oxide (20 mmol), l-phenylalanine (0.16 mmol) and CH2Cl2 (1 mL) were added into a 15 mL stainless autoclave with a magnetic stirrer, and CO2 (liquid, 3.2 MPa) was charged into the reactor at r.t. The initial pressure was generally adjusted to 6 MPa at 130 °C. The autoclave was heated at that temperature for 48 h, and the pressure was kept constant during the reaction. After the reaction, the reactor was cooled to 0 °C, and extra CO2 was vented slowly. The crude product was analyzed by a gas chromatograph, compared with authentic sample, and the yields were determined by GC using tridecane as internal standard. The crude product (yield: 100% by GC) was purified by distillation and propylene carbonate was obtained in 93% isolated yield. The cyclic carbonate was identified by IR, GC/MS (HP6890/5973) and 400 MHz NMR spectroscopy.

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Spectroscopic data of the cyclic carbonates:
4-Methyl-1,3-dioxolan-2-one (2a): IR (neat): 1795 (C=O) cm-1. MS (EI): m/z = 102 [M+]. 1H NMR (400 MHz, TMS, CDCl3): δ = 1.48 (d, J = 3.6 Hz, 3 H, CH3), 4.01 (t, J = 8.4 Hz, 1 H, CH), 4.53 (t, J = 8.0 Hz, 1 H, CH), 4.81-4.86 (m, 1 H, CH).
4-Chloromethyl-1,3-dioxolan-2-one (2b): IR (neat): 1790 (C=O) cm-1. MS (EI): m/z = 136 [M+]. 1H NMR (400 MHz, TMS, CDCl3): δ = 3.72-3.74 (m, 2 H, CH2), 4.38 (q, J = 6.0 Hz, 1 H, CH), 4.57 (t, J = 8.4 Hz, 1 H, CH), 4.91-4.94 (m, 1 H, CH).
4-Phenyl-1,3-dioxolan-2-one (2c): IR (neat): 1816 (C=O) cm-1. MS (EI): m/z = 164 [M+]. 1H NMR (400 MHz, TMS, CDCl3): δ = 4.31-4.35 (m, 1 H, CH), 4.76-4.82 (m, 1 H, CH), 5.66 (t, J = 8.0 Hz, 1 H, CH), 7.32-7.44 (m, 5 H, C6H5).
4-Butyl-1,3-dioxolan-2-one (2d): IR (neat): 1798 (C=O) cm-1. MS (EI): m/z = 145 [M+]. 1H NMR (400 MHz, TMS, CDCl3): δ = 0.91 (t, J = 4.8 Hz, 3 H, CH3), 1.32-1.38 (m, 4 H, CH2), 1.65-1.78 (m, 2 H, CH2), 4.04 (dd, J = 7.2, 8.4 Hz, 1 H, CH), 4.50 (t, J = 8.0 Hz, 1 H, CH), 4.64-4.71 (m, 1 H, CH).
4-Phenoxymethyl-1,3-dioxolan-2-one (2e): IR (neat): 1796 (C=O) cm-1. MS (EI): m/z = 194 [M+]. 1H NMR (400 MHz, TMS, CDCl3): δ = 4.13 (dd, J = 3.6, 10.4 Hz, 1 H, CH), 4.22 (dd, J = 4.0, 10.4 Hz, 1 H, CH), 4.52 (dd, J = 6.0, 8.8 Hz, 1 H, CH), 4.60 (t, J = 4.4 Hz, 1 H, CH), 4.99-5.02 (m, 1 H, CH), 6.89 (d, J = 7.6 Hz, 2 H, Ph), 7.00 (t, J = 7.6 Hz, 1 H, Ph), 7.29 (dd, J = 7.6, 8.4 Hz, 2 H, Ph).
4-Allyloxymethyl-1,3-dioxolan-2-one (2f): IR (neat): 1796 (C=O) cm-1. MS (EI): m/z = 159 [M+ + H]. 1H NMR (400 MHz, TMS, CDCl3): δ = 3.21-3.68 (m, 2 H, CH2), 4.02-4.04 (m, 2 H, CH2), 4.37 (dd, J = 6.0, 8.4 Hz, 1 H, CH), 4.48 (t, J = 8.4 Hz, 1 H, CH), 4.75-4.80 (m, 1 H, CH), 5.18-5.28 (m, 2 H, CH2), 5.81-5.87 (m, 1 H, CH).
Cyclohexyl-1,3-dioxolan-2-one (2g): IR (neat): 1801 (C=O) cm-1. MS (EI): m/z = 142 [M+]. 1H NMR (400 MHz, TMS, CDCl3): δ = 1.37-1.41 (m, 2 H, CH2), 1.57-1.61 (m, 2 H, CH2), 1.85-1.89 (m, 4 H, CH2), 4.63-4.68 (m, 2 H, CH).