A Two-Directional Approach to Enantiopure 1,4-Difluoro-cyclohexenes: Synthesis of Difluorinated Cyclitol Analogues
作者:Sophie Purser、Timothy D. W. Claridge、Barbara Odell、Peter R. Moore、Véronique Gouverneur
DOI:10.1021/ol8017402
日期:2008.10.2
Enantiopure 1,4-difluoro-cyclohexenes were prepared from readily available acetonide-protected (3S,4S)-hexa-1,5-diene-3,4-diol. In a two-directional mode, a double cross-metathesis reaction using allyltrimethylsilane as the olefinic partner, followed by electrophilic fluorination, afforded diastereomeric acetonide-protected 3,6-difluoro-octa-1,7-diene-4,5-diols. These dienes were found to be suitable substrates for ring-closing metathesis, delivering cyclohexenes featuring fluorine atoms on the two allylic positions flanking the double bond. Upon dihydroxylation, novel difluorinated cyclitol analogues were formed.