Nucleophilic Dechlorocarbomethoxylation of (E)-Methyl β-Chloro-α-methyl-β-(3-bromo- 2,4,6-trimethylphenyl)acrylate

摘要

Vinylic substitution of alkyl β-halocinnamates by nucleophiles was extensively studied. When the α-position is substituted, e.g., with an α-carboalkoxy or an α-cyano group, the reaction usually proceeds by the addition-elimination route (eq 1), whereas with an α-hydrogen ArC(X)=C(R)CO_2Me + Nu~- → X = Cl, Br; Nu~- = SR′, OR′, F~-R = CN, CO_2Me ArC(Nu)=C(R)CO_2Me (1) ArC(X)=CHCO_2Me + Nu~- → ArC≡CCO_2Me X = Cl; Nu~- = R′O~- (2) derivative substitution via addition-elimination or elimination to the acetylene may take place (eq 2), We have found that when the aryl group is bulky, a different reaction course, i.e., nucleophilic dechlorocarbomethoxylation with, formation of an acetylene, takes place.