A novel Mannich-type reaction: Lanthanide triflate-catalyzed reactions of N-(α-aminoalkyl)benzotriazoles with silyl enolates
作者:Shū Kobayashi、Haruro Ishitani、Susumu Komiyama、Daniela C. Oniciu、Alan R. Katritzky
DOI:10.1016/0040-4039(96)00671-5
日期:1996.5
In the presence of a catalytic amount of a lanthanide triflate, N-(α-aminnoalkyl)benzotriazoles reacted with silylenolates to give the corresponding β-amino ketone or ester derivatives in high yields with high diastereoselectivities.
The first observation of the stereospecificity in the benzyne-olefin [2 + 2] cycloaddition is described. The key points reside in (1) the efficient method for generating benzyne species by the halogen-lithium exchange reaction of ortho-halo aryl triflates, and (2) the choice of ketene silyl acetal as the partner olefin.
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)
Practical preparation of α-hydroxy-β-amino ester units; Stereoselective synthesis of taxol side chain and norstatine
作者:Kouji Hattori、Hisashi Yamamoto
DOI:10.1016/s0040-4020(01)86992-1
日期:1994.2
An asymmetric reaction of chiral imines with α-silyloxy ketene acetals mediated by chiral boron reagents is described. The key to its success is the use of the chiral boron complex prepared in situ from (R)- or (S)-binaphthol and B(OPh)3. Both diastereomers of α-hydroxy-β-amino ester units are successfully prepared with high selectivities by the chiral boron reagents depending on the geometry of the
One-pot Synthesis of β-Amino Esters from Aldehydes Using Lanthanide Triflate as a Catalyst
作者:S Kobayashi
DOI:10.1016/00404-0399(50)1096z-
日期:1995.8.7
One-pot synthesis of a beta-amino ester from an aldehyde, an amine, and a silyl enolate has been achieved using a lanthanide triflate as a catalyst. One-pot preparation of a beta-lactam from an aldehyde is also described.