Synthesis of Functionalized Dialkyl Cyclobutane-1,1-dicarboxylates and Alkyl 5,6-Dihydro-4H-pyran-3-carboxylates via Michael-Induced Ring Closure of δ-Chloro-α,β-Unsaturated Diesters and Ketoesters

Abstract

Michael-induced ring closure (MIRC) of dimethyl 2-(3-chloro-2,2-dimethylpropylidene)malonate, upon treatment with sodium tert-butylthiolate, sodium methoxide or sodium cyanide in methanol, provided a short and efficient synthesis of new 2-functionalized cyclobutane-1,1-dicarboxylic esters. Under similar conditions, methyl 2-acetyl-5-chloro-4,4-dimethylpent-2-enoate afforded 4-functionalized methyl 5,6-dihydro-4H-pyran-3-carboxylates as the MIRC products.