Enantioselective Thiourea-Catalyzed Additions to Oxocarbenium Ions
作者:Sarah E. Reisman、Abigail G. Doyle、Eric N. Jacobsen
DOI:10.1021/ja801514m
日期:2008.6.1
Asymmetric, catalytic reactions of oxocarbeniumions are reported. Simple, chiral urea and thiourea derivatives are shown to catalyze the enantioselective substitution of silyl ketene acetals onto 1-chloroisochromans. A mechanism involving anion binding by the chiral catalyst to generate a reactive oxocarbeniumion is invoked. Catalysts bearing tertiary benzylic amide groups afforded highest enantioselectivities
Stereoelectronic effects in the ring cleavage of methyl glycopyranosides using dimethylboron bromide
作者:Yvan Guindon、Paul C. Anderson
DOI:10.1016/s0040-4039(00)95447-9
日期:1987.1
Treatment of methyl D-glycopyranosides with dimethylboron bromide followed by a nucleophile gives acyclic products resulting from selective cleavage of the ring carbon-oxygen bond. The results are rationalized based on stereoelectronic considerations.