New cyclopropyl building blocks for organic synthesis, Part 61 - Catalyzed nucleophilic substitution on cyclopropenylmethyl esters - Reactions via a 1,2-methano-pi-allylpalladium intermediate

Palladium-catalyzed substitutions on primary and secondary 3,3-dimethylcyclopropenylmethyl carbonates 6a-OR, readily prepared by reaction of 3,3-dimethylcyclopropenyllithium with formaldehyde and subsequent acylation with methyl or benzyl chloroformate, with dimethylmalonate enolates and bissulfonyl-stabilized carbanions occurred regioselectively to give derivatives 12-16 in good yields (43-81%). The reaction of the tertiary acetate 6c-Me gave a mixture of the regioisomeric products 17 (43%) and 18 (27%).