Prins Cyclization of Bis(silyl) Homoallylic Alcohols to Form 2,6-<i>cis</i>-Tetrahydropyrans Containing a Geometrically Defined Exocyclic Vinylsilane: Efficient Synthesis of Ring B of the Bryostatins
作者:Ji Lu、Zhenlei Song、Yuebao Zhang、Zubao Gan、Hongze Li
DOI:10.1002/anie.201201323
日期:2012.5.29
Charming: Prins cyclization of a bis(silyl) homoallylic alcohol with an aldehyde shows excellent cis and Z selectivity to form tetrahydropyrans containing a geometricallydefinedexocyclic vinylsilane. This reaction was used as the key step in the synthesis of ring B of the bryostatins.
[1,5]-Brook rearrangement: an overlooked but valuable silyl migration to synthesize configurationally defined vinylsilane. The unique steric and electronic effects of geminal bis(silane)
geminal bis(silyl) homoallylic alcohol is described. The unique steric and electroniceffects of geminal bis(silane) were found to be crucial for promoting this long-range silyl migration, as well as for facilitating the subsequent gamma/Z-selective addition of silyl allyllithium with carbonyl compounds to synthesize diverse configurationally defined Z-vinylsilanes.