Deconjugation-Alkylation of Ethyl 3-(Trimethylstannyl)-2-alkanoates. Stereocontrolled Synthesis of Ethyl 2-Alkylidene-3-methylenecyclobutanecarboxylates
Alkylation of ethyl (E)- and (Z)-3-(trimethylstannyl)-2-alkenoates with 2,3-dibromopropene, followed by (Ph3P)Pd-catalyzed cyclization of the resultant products, provides ethyl (Z)- and (E)-2-alkylidene-3-methylenecyclobutanecarboxylates, respectively, in good yields (60-79percent).