Ring-Opening of 1-CF3-Substituted Epoxy Ethers with Carboxylic, Thiocarboxylic, and Phosphinic Acids in Basic Medium and in Hexafluoro-2-propanol
摘要:
Ring-opening of 1-CF3-substituted epoxy ethers with carboxylic acids was achieved in Et3N as solvent, and alpha-CF3-substituted acyloins and corresponding esters were obtained in good yields. In hexafluoro-2-propanol (HFIP) as solvent, the carboxylic acids acted as nucleophiles, and alpha-carbonyloxy trifluoromethyl ketones were isolated in good yields. After reduction, CF3-substituted glycols were obtained as monoesters on one or the other hydroxy group. This reaction also allowed the preparation of alpha-carbonylsulfanyl- and alpha-phosphoryloxy trifluoromethyl ketones and corresponding alcohols. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
Ring-Opening of 1-CF3-Substituted Epoxy Ethers with Carboxylic, Thiocarboxylic, and Phosphinic Acids in Basic Medium and in Hexafluoro-2-propanol
摘要:
Ring-opening of 1-CF3-substituted epoxy ethers with carboxylic acids was achieved in Et3N as solvent, and alpha-CF3-substituted acyloins and corresponding esters were obtained in good yields. In hexafluoro-2-propanol (HFIP) as solvent, the carboxylic acids acted as nucleophiles, and alpha-carbonyloxy trifluoromethyl ketones were isolated in good yields. After reduction, CF3-substituted glycols were obtained as monoesters on one or the other hydroxy group. This reaction also allowed the preparation of alpha-carbonylsulfanyl- and alpha-phosphoryloxy trifluoromethyl ketones and corresponding alcohols. (C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
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
Unusual reactions of secondary amino acids with trifluoroacetic anhydride: A novel access to α-trifluoromethylated acyloins
作者:Masami Kawase
DOI:10.1016/0040-4039(94)88187-1
日期:1994.1
A new fragmentation reaction of secondary α-amino acids with trifluoroaceticanhydride under Dakin-West reaction conditions proceeds through oxazolium salt intermediates followed by ring cleavage to form α-trifluoromethylated acyloins in good yields.
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.