Short asymmetric syntheses of homoallylic, homopropargylic and allenic silylated primary amines
摘要:
Amino alcohols derived from phenylglycinol and having vinyl-, alkynyl- or allenylsilane moieties were transformed in the corresponding primary amines in two steps: oxidative cleavage of phenylglycinol and transimination with phenylhydrazine. This methodology gave general access to enantiomerically enriched amines without loss of enantioselectivity. (C) 2004 Elsevier Ltd. All rights reserved.
Diastereoselective reactions between (S)-phenylglycinol-derived oxazolidines and two unsaturated organolithium reagents afforded chiral beta-amino alcohols having vinyl and alkynylsilane moieties. When the same reactions were performed in the presence of titanium isopropoxide, a dramatic change of regioselectivity was observed, from the alpha- to the gamma-position, thus producing beta-amino alcohols
The Intriguing Reactivity of Functionalized β-Amino Alcohols with Glyoxal: Application to a New Expedient Enantioselective Synthesis of <i>trans</i>-6-Alkylpipecolic Acids
New beta-amino alcohols possessing a vinylsilane moiety were reacted with glyoxal to produce lactones that were transformed in three steps in enantiopure pipecolic acid derivatives. The key step was a totally diastereoselective ene-iminium cyclization, whose mechanism can be viewed as a direct cyclization of the vinylsilane moiety onto the iminium ion. The reactivity of two beta-amino alcohols having