55136-54-4Relevant academic research and scientific papers
ELECTROPHILIC ADDITION TO ACETYLENES. VIII. STEREOCHEMISTRY OF THE ADDITION OF ALKYL CHLOROMETHYL ETHERS TO PHENYL-SUBSTITUTED ALKYNES
Marcuzzi, Franco,Melloni, Giovanni,Zucca, Maria Vincenza
, p. 219 - 226 (2007/10/02)
The zinc-chloride-catalyzed addition of chloromethyl ethyl ether and chloromethyl methyl ether to some phenyl alkynes and to 2-butyne in dichloromethane was studied.In most cases the reactions afforded mixtures of the 1:1 addition products and of the corresponding dichloro derivatives, in which the allylic alkoxyl group was replaced by a chloro atom.The characteristics of the reaction and the stereochemistry of the addition are consistent with a stepwise electrophilic addition mechanism, with formation of vinyl cations by attack of alkoxy-substituted carbenium ions to the triple bond and subsequent preferential attack by the nucleophile Cl- on the less hindered side of the intermediates.However, at variance with previous studies, E-Z isomerization of the addition products under the reaction conditions was observed, which made less clear-cut the stereochemical data.This isomerization reaction and the formation of dichloro derivatives are explained in terms of a subsequent reaction of the 1:1 addition products with the alkyl chloromethyl ether, through the intermediacy of γ-phenyl-substituted allylic cations.
