Synthesis 2011(21): 3435-3438  
DOI: 10.1055/s-0030-1260222
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

An Efficient Direct Asymmetric Synthesis of 3-Substituted Phthalides

Zhan-Bin Zhang, Yong-Qin Lu, Xin-Fang Duan*
Department of Chemistry, Beijing Normal University, Beijing 100875, P. R. of China
Fax: +86(10)58802075; e-Mail: xinfangduan@vip.163.com;
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Publikationsverlauf

Received 22 July 2011
Publikationsdatum:
13. September 2011 (online)

Abstract

A facile, two-step, asymmetric synthesis of 3-substituted phthalides has been developed. The enantiopure amide, obtained through coupling of 2-iodobenzoic acid with (S)-1-(pyrrolidin-2-ylmethyl)-1H-imidazole, was magnesiated using isopropylmagnesium chloride. Corresponding reactions with a range of aldehydes were carried out in situ by either direct addition or transmetallation using zinc(II) chloride. Intramolecular esterification of the adduct allowed the versatile asymmetric synthesis of phthalides in up to 88% enantiomeric excess.