Synthesis and conformational study of chiral oxepines: the baylis-hillman reaction and RCM approach with sugar aldehyde

TitleSynthesis and conformational study of chiral oxepines: the baylis-hillman reaction and RCM approach with sugar aldehyde
Publication TypeJournal Article
Year of Publication2009
AuthorsJadhav, VH, Bande, OP, Pinjari, RV, Gejji, SP, Puranik, VG, Dhavale, DD
JournalJournal of Organic Chemistry
Volume74
Issue17
Pagination6486-6494
Date PublishedSEP
ISSN0022-3263
Abstract

The Baylis-Hillman reaction of 3-O-allyl-alpha-D-xylo-pentodialdo-1,4-furanose 3 afforded a diastereomeric mixture of D-gluco- and L-ido-configured alpha-methylene-beta-hydroxy esters 4a and 4b, respectively, in a ratio of 2:3. Reduction of the ester functionality in 4a/4b gave alcohols 5a/5b. The diene thus formed in 5a/5b was subjected to ring-closing metathesis (Grubbs' second-generation catalyst) to afford oxa-bicyclic ring system 6a/6b in high yield. Further manipulation of the aectonide functionality in 6a and 6b afforded new polyhydroxylated oxepines 1a/2a and 1b/2b, respectively. The (1)H NMR of oxepines 1a and 1b in D(2)O showed doubling of signals indicating their existence in two different rotamers/conformers. This fact was substantiated by calculating energetics of 1 and 2 conformers using the density functional theory and correlating the calculated (1)H NMR chemical shift pattern with that of the experimental spectra.

DOI10.1021/jo900660q
Type of Journal (Indian or Foreign)

Foreign

Impact Factor (IF)

4.002

Divison category: 
Center for Material Characterization (CMC)