Synthesis and chemical transformations of diazolyl α,α-difluoroacetates
作者:Oleksandr V. Geraschenko、Vitalii V. Solomin、Bohdan V. Vashchenko、Pavlo Khodakivskyi、Andrey A. Tolmachev、Oleksandr O. Grygorenko
DOI:10.1016/j.jfluchem.2019.109407
日期:2020.1
Optimized protocols for the synthesis of diazolyl α,α-difluoroacetates via deoxofluorination of the corresponding glyoxylates with Morph-DAST are described. The method allowed the preparation of the title fluoridated building blocks in 73–96% yield on up to 15 g scale. Utility of the hetaryl α,α-difluoroacetates was demonstrated by the synthesis of advanced building blocks for medicinal chemistry,
Ethyl 2-azolylglyoxylates react smoothly with o-phenylenediamines and 1,2-diaminocyclohexane in acetonitrile at room temperature to give the corresponding 3-azolylquinoxalin-2(1H)-ones and their saturated analogues in good to excellent yields.
Facile Synthesis of 2-(2-Ethoxy-1,2-dioxoethyl)azoles
C-Acylation of N-substituted imidazoles with ethyl oxalyl chloride in the presence of N,N-diisopropylethylamine as a base afforded 2-(2-ethoxy-1,2-dioxoethyl)imidazoles in 83-95% yield. Application of this synthetic protocol to thiazoles and triazoles led to the corresponding 2-ethoxy-1,2-dioxoethyl derivatives in 40-51% yield.
Ethyl azol-2-ylglyoxylates react smoothly with acetone in the presence of catalytic amounts of proline and trifluoroacetic acid to give the corresponding azolyl aldols in 93-98% yield. The products are easily transformed into azolyl pyridazinones in 85-98% yield by cyclization with hydrazine hydrate.