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Synlett 2006(15): 2486-2488  
DOI: 10.1055/s-2006-950412
LETTER
© Georg Thieme Verlag Stuttgart · New York

Facile Synthesis of Aryl α-Keto Esters via the Reaction of Aryl Diazoacetate with H2O and DEAD

Zhenqiu Guoa,b, Haoxi Huanga,b, Qingquan Fua,b, Wenhao Hu*a
a Key Laboratory for Asymmetric Synthesis and Chirotechnology of Sichuan Province and Union Laboratory of Asymmetric Synthesis, Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu 610041, P. R. of China
Fax: +86(28)85229250; e-Mail: huwh@cioc.ac.cn;
b Graduate School of Chinese Academy of Sciences, Beijing, P. R. of China
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Publication History

Received 28 April 2006
Publication Date:
08 September 2006 (online)

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Abstract

A facile synthesis of aryl aα-keto esters in high yields is reported involving the reaction of aryl diazoacetate with H2O and diethyl azodicarboxylate (DEAD) catalyzed by dirhodium acetate.

Key words

α-keto ester - α-diazoacetate - oxonium ylide - fragmentation

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Typical Procedure
To a refluxing toluene (20 mL) solution of Rh2 (OAc)4 (13.4 mg, 1 mol%), H2O (59.4 mL, 3.3 mmol) and DEAD (574.7 mg, 3.3 mmol) was added phenyl diazoacetate 1a (528.5 mg, 3 mmol) in 18 mL of toluene over 1 h via a syringe pump. After stirring for additional 3 h, the reaction mixture was cooled to r.t. and the solvent was removed. The crude product was purified by flash chromatography on silica gel by using 3% EtOAc-light PE as eluent to give an white oil 2a (448.2 mg, 2.73 mmol), yield 91%.

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Analytical data of 7: Rotamer ratio = 2.3:1; major rotamer: 1H NMR (300 MHz, CDCl3): δ = 7.76-7.67 (m, 2 H), 7.38-7.29 (m, 3 H), 6.24 (s, 1 H), 4.29-4.02 (m, 4 H), 3.88 (s, 3 H), 3.70 (s, 3 H), 1.32-1.13 (m, 6 H). 13C NMR (75 MHz, CDCl3): δ = 167.3, 156.0, 155.2, 136.8, 135.8, 128.2, 127.7, 127.2, 126.8, 92.8, 62.6, 61.6, 53.4, 52.2, 13.8, 13.7. HRMS: m/z calcd for C16H22N2O7; 377.1319; found: 377.1321 [M + Na]+.