Highly selective enolization method for heteroatom substituted esters; its application to the ireland ester enolate claisen rearrangement
作者:Kouji Hattori、Hisashi Yamamoto
DOI:10.1016/s0040-4020(01)81109-1
日期:1994.3
A method for the stereoselective synthesis of silylketeneacetals from α-siloxy esters, β-hydroxy esters, and α-aminoesters is described. Internal quench with excess trimethylsilyl chloride of the lithium enolate at −100 °C, which is generated using a hindered base, LTMP, leads to the selective formation of E-silyl keteneacetal. In contrast, the deprotonation at −100 °C using LHMDS in THF-HMPA (4:1)
Air-Stable, Storable, and Highly Selective Chiral Lewis Acid Catalyst
作者:Masaharu Ueno、Haruro Ishitani、Shū Kobayashi
DOI:10.1021/ol026452t
日期:2002.10.1
[GRAPHICS]An air-stable, storable, and highly selective chiral Lewis acid catalyst for asymmetric Mannich-type reactions has been developed, The catalyst can be stored for more than three months in air at room temperature without loss of activity, Moreover, it has also been demonstrated that the catalyst can be recovered and reused.
Highly selective generation and application of (E)- and (Z)-silyl ketene acetals from .alpha.-hydroxy esters
作者:Kouji Hattori、Hisashi Yamamoto
DOI:10.1021/jo00072a005
日期:1993.9
A method for the stereoselective synthesis of silyl ketene acetals from a-hydroxy esters is described. Internal quench with excess TMSCI of the lithium enolate at -100-degrees-C, which is generated using a hindered base, LTMP, leads to the selective formation of (E)-silyl ketene acetal. In contrast, the deprotonation at -100-degrees-C using LHMDS in THF-HMPA (4:1), followed by treatment with tert-butyldimethylsilyl chloride affords the (Z)-silyl ketene acetal selectively. The method can be applied to the stereoselective reaction of the Ireland ester enolate Claisen rearrangement and aldol synthesis.