Synlett 2003(9): 1334-1338
DOI: 10.1055/s-2003-40323
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Lasonolide A: Synthesis of A and B Rings via a Cycloetherification Strategy

David J. Hart*, Suzanne Patterson, James P. Unch
Department of Chemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, Ohio 43210, USA
Fax: +1(614)2921685; e-Mail: hart@chemistry.ohio-state.edu;
Further Information

Publication History

Received 10 April 2003
Publication Date:
30 June 2003 (online)

Abstract

Syntheses of tetrahydropyrans ent-2 and ent-3, substructures of the A and B rings of the enantiomer of lasonolide A (1), are described. The syntheses of ent-2 and ent-3 feature highly stereo­selective cycloetherification reactions of bis-homoallylic alcohols 7 and 8.

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We thank Professor Lee for providing us with copies of 1H and 13C NMR spectra of 2 and 3.

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We thank Dr. Judith C. Gallucci for determining the structure of 40 at the OSU Chemistry Department Crystallographic Facility.

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During the course of this work we have examined cyclizations of several structures related to 8 (replace C6
p-methoxystyryl group with phenyl, 2-furyl, styryl). In all cases the structure corresponding to 35 was the major product in 60-70% yield. In one case (styryl) a minor diastereomer (5%) was detected in which all substituents were equatorially disposed on the tetrahydropyran ring with the exception of the benzyloxymethyl group (axially disposed).

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Some of the reagents used in Schemes [1] and [2] are toxic (for example PhSeCl). Appropriate care should be used in the handling and disposal of these materials.