Trifluoroacetylation of unsymmetrical ketone acetals. A convenient route to obtain alkyl side chain trifluoromethylated heterocycles

被引：93

作者：

Bonacorso, HG ^{[1
]}

Martins, MAP ^{[1
]}

Bittencourt, SRT ^{[1
]}

Lourega, RV ^{[1
]}

Zanatta, N ^{[1
]}

Flores, AFC ^{[1
]}

机构：

[1] Univ Fed Santa Maria, Dept Quim, BR-97105900 Santa Maria, RS, Brazil

来源：

JOURNAL OF FLUORINE CHEMISTRY | 1999年 / 99卷 / 02期

关键词：

beta-alkoxyvinyl trifluoromethyl ketones; unsymmetrical ketone dimethyl acetals; trifluoromethylated heterocycles;

D O I：

10.1016/S0022-1139(99)00146-3

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

A convenient method to obtain beta-alkyl-beta-methoxyvinyl trifluoromethyl ketones [CF3COCH=C(OMe)R, where R = Et, n-Pr, i-Pr, i-Bu, t-Bu, -(CH2)(2)OMe] from the regiospecific acylation of kinetic enol ether generated in situ is reported. The unsymmetrical ketone dimethyl acetals react with trifluoroacetic anhydride in the presence of pyridine using dry chloroform as solvent with a temperature range of 25-60 degrees C. These acetals [R-C(OMe)(2)Me] are obtained from the reaction of alkyl methyl ketones with trimethyl orthoformate in the presence of p-toluenesulfonic acid as catalyst in pure methanol as solvent. The new acetylated enol ethers proved to be versatile building blocks for the construction of interesting alkyl trifluoromethyl substituted heterocycles. Thus, examples of isoxazoline, pyrazoline, pyrazole and pyrimidinone have been obtained in good yields (62-79%). (C) 1999 Elsevier Science S.A. All rights reserved.

引用

页码：177 / 182

页数：6

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