Carbocyclisation of zinc enolates onto unactivated double bonds: a mechanistic point of view

The recent results concerning the carbocyclisation reaction of zinc enolates onto an unactivated double bond are summarized, particularly on the stereochemical point of view. The implications of the observed stereochemistries on the mechanism of the reaction (O-centred zinc enolate vs C-centred zinc enolate) are discussed. Some new results leading stereoselectively to 1-amino-1-carbomethoxy-2-methyl cyclopentanes are reported, as well as the consequences of the observed stereochemistry as a strong evidence for a C-centred zinc enolate intermediate.