CYCLOPROPYL BUILDING-BLOCKS FOR ORGANIC-SYNTHESIS, 43 - RING-OPENING OF METHYLENECYCLOPROPANE MOIETIES IN THE PALLADIUM-CATALYZED CROSS-COUPLING OF METHYLENECYCLOPROPYL BROMIDES WITH METALATED CH-ACIDIC COMPOUNDS

Palladium-catalyzed cross-coupling reactions of bromo(methylenecyclopr opanes) 1c, 2c with the sodium enolate of dimethyl malonate 4a and the chlorozinc enolates of the glycine equivalent (diphenylmethyleneamino )acetate 4c and diethyl malonate 4d, respectively, have been found to proceed with opening of the three-membered ring in each case, to give the corresponding dienyl-substituted CH-acidic compounds 5-7 in modera te to good yields. On the other hand, coupling of bicyclopropylidenylz inc chloride (2d) with diethyl bromomalonate (4e) and the electrophili c glycine equivalent ethyl 2-acetoxy-2-(diphenylmethyleneamino)acetate (4f) gave 7 and 6 in 27 and 29% yield, respectively.