A convenient synthesis of α-trifluoremethylated and α-perfluoroalkylated acyloins from α-hydroxy acids
作者:Masami Kawase、Teruo Kurihara
DOI:10.1016/0040-4039(94)88284-3
日期:1994.10
A novel transformation of α-hydroxy acids to α-trifluoremethylated and α-perfluoroalkylated acyloins was efficiently realized by utilizing trifluoroacetic or perfluoroalkylcarboxylic anhydrides in the presence of pyridine, in which probable intermediates were meso-ionic 1,3-dioxolium-4-olates.
Convenient Synthesis of .ALPHA.-Trifluoromethylated Acyloins from .ALPHA.-Hydroxy or .ALPHA.-Amino Acids.
作者:Masami KAWASE、Setsuo SAITO、Teruo KURIHARA
DOI:10.1248/cpb.48.1338
日期:——
acyloins (2 and 6) have been prepared from alpha-hydroxy acids (1), N-acylprolines (5) or N-acyl-N-alkyl alpha-amino acids (8) by novel transformation reactions with trifluoroacetic anhydride (TFAA) in the presence of pyridine. The former reaction of 1 could proceed through mesoionic 1,3-dioxolium-4-olates, whereas the latter two reactions of alpha-amino acids (5 and 8) could involve mesoionic 1,3-oxazolium-5-olates
study has led to the development of a novel, highly efficient, 1,2-perfluoro-alkyl/-aryl migration process in reactions of hydrate of 1-perfluoro-alkyl/-aryl-1,2-diketones with alcohols, which are promoted by a Zn(II)/bisoxazoline and form α-perfluoro-alkyl/-aryl-substituted α-hydroxy esters. With (-)-8-phenylmenthol as the alcohol, the corresponding menthol esters are generated in high yields with