[Reaction: see text] A stereocontrolled convergent synthesis of the annonaceous acetogenin pyranicin (1) is presented. Asymmetric Horner-Wadsworth-Emmons (HWE) reactions were used to access keyintermediates. The tetrahydropyran derivative 2 was obtained via an asymmetric desymmetrization of the meso-dialdehyde 6, and the butenolide fragment was constructed using a stereoconvergent reaction sequence
The stereocontrolled formation of cyclic vicinal cis-diols via a samarium diiodide pinacol coupling of dialdehydes
作者:Jose Luis Chiara、Walter Cabri、Stephen Hanessian
DOI:10.1016/s0040-4039(00)92024-0
日期:1991.2
Aliphatic 1,5- and 1,6 dialdehydes with and without α-substituents, as well as derivatives of carbohydrate dialdehydes undergo a pinacol coupling reaction in the presence of SmI2 to give cis-diols as the preponderant products. When α-alkoxy groups are present, the diol has an orientation that is opposite to such groups.