One-Stage Procedure of Synthesis of Highly Reactive alpha-Ghloro-beta-ketoacetals.4-Chloropyrazoles from alpha-Chloro-beta-ketodimethoxyacetals

摘要

Conditions were developed where the reaction of alkyl 1,2-dichlorovinyl ketones with alcohols and 1,2-dihydroxybenzenes led to the formation of the corresponding open-chain and cyclic alpha-chloro-beta-ketoacetals.The reaction of alpha-chloro-beta-alkylketodimethoxyacetals with alkyl-,benzyl-,and arylhydrazines resulted in 1,3-substituted 4-chloropyrazoles in 70-90% yields demonstrating that primarily formed 2,2-dimethoxy-1-chloroethyl alkyl ketones hydrazones underwent heterocyclization.