Nucleophilic Epoxidation of α‘-Hydroxy Vinyl Sulfoxides
摘要:
The nucleophilic epoxidation of a variety of alpha'-(1-hydroxyalkyl) vinyl sulfones and sulfoxides has been studied. The sulfones give rise to anti oxiranes with modest (E) or excellent (Z) selectivities and in good yields. The (E)-sulfoxides display low reactivity within a reinforcing/nonreinforcing scenario. The use of t-BuOOLi in Et2O allows for a highly syn-selective epoxidation-oxidation. The (Z)-sulfoxides display a remarkably high reactivity under these conditions. The reinforcing (S,Ss) diastereomers (3e-g) yield hydroxy sulfinyl oxiranes with high yields and selectivities. In contrast, the (R,Ss) diastereomers (4e-g) show diminished reactivities and a very substrate-dependent stereochemical outcome. The structure of these oxiranes has been secured by chemical correlations and an X-ray crystal structure.
Stereoselective Dichlorination of Allylic Alcohol Derivatives to Access Key Stereochemical Arrays of the Chlorosulfolipids
作者:Grant M. Shibuya、Jacob S. Kanady、Christopher D. Vanderwal
DOI:10.1021/ja804167v
日期:2008.9.17
Dichlorination of (Z)-allylic trichloroacetates efficiently and stereoselectively generates the syn,syn hydroxydichloride stereotriad that is prevalent in the understudied polychlorinated sulfolipid class of natural products. Further, the dichlorination of a (Z)-allylic chlorohydrin affords with high selectivity a stereotetrad present in one of the chlorosulfolipids.