Download PDF
Synthesis 2006(22): 3915-3917  
DOI: 10.1055/s-2006-950295
PSP
© Georg Thieme Verlag Stuttgart · New York

Practical and Robust Method for the Preparation of Seebach and Fráter’s Chiral Template, cis-2-Substituted 5-Methyl(or Phenyl)-1,3-dioxolan-4-ones

Ryohei Nagase, Yumiko Oguni, Tomonori Misaki, Yoo Tanabe*
Department of Chemistry, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Japan
Fax: +81(79)5659077; e-Mail: tanabe@kwansei.ac.jp;
Further Information

Publication History

Received 26 May 2006
Publication Date:
09 October 2006 (online)

    Permissions and Reprints All articles of this category

Abstract

A practical and highly stereoselective method for the preparation of three cis-2-substituted 5-methyl (or phenyl)-1,3-dioxolan-4-ones 3a and 7a (Seebach and Fráter’s chiral template), and a new modified analogue 7b has been developed. The present robust method utilized reactive 2-methoxy-1,3-dioxolane intermediate 4 and the reaction proceeded more smoothly under milder reaction conditions than in previously reported methods. Desired products 3a, 7a, and 7b were easily purified by distillation or recrystallization, i.e. column chromatographic purification, was not necessary.

Key words

(S)-lactic acid - (S)-mandelic acid - cyclocondensation - acid catalyst - 2,5-disubstituted-1,3-dioxolan-4-ones

6

In our hands, comparable experiments using pentane and heptane (bp 98 °C) as solvents revealed that they have a significant effect on the stereoselectivity; cis/trans = 97:3 (pentane) and 54:46 (heptane). The direct method largely depends on the reaction temperature of azeotropic boiling points.