Enantiospecific Syntheses of (+)-Crotepoxide, (+)-Boesenoxide, (+)-β-Senepoxide, (+)-Pipoxide Acetate, (−)-<i>iso</i>-Crotepoxide, (−)-Senepoxide, and (−)-Tingtanoxide from (−)-Quinic Acid<sup>1</sup>
作者:Tony K. M. Shing、Eric K. W. Tam
DOI:10.1021/jo970907o
日期:1998.3.1
A convenient strategy that is ideally suited for the construction of all the naturally occurring cyclohexane diepoxides and cyclohexene epoxides is described. The key intermediate 12, a 1,3-cyclohexadiene, has been prepared from (-)-quinic acid in 11 steps with 18% overall yield. Singlet oxygen photooxygenation of the 1,3-cyclohexadiene followed by rearrangement of the resultant endoperoxides with either cobalt-meso-tetraphenylporphyrin or trimethyl phosphite afforded enantiopure (+)-crotepoxide, (+)-boesenoxide, and (-)-iso-crotepoxide or (-)-senepoxide, (+)-beta-senepoxide,(+)-pipoxide acetate, and (-)-tingtanoxide, respectively.