Bulky Cinchonine Derivatives as Phase-Transfer Catalysts in Vinylic Substitution Reactions

Significance

The first catalytic enantioselective nucleophilic vinylic substitution reaction is described. With the use of a new highly bulky cinchonine derivative as chiral phase-transfer catalyst (PTC), products of the general form 3 are accessible in good to high yields and Z/ E ratios, as well as with high enantioselectivities. Substitution of the vinylic chloride from activated Z-alkenes 2 by nucleophiles derived from cyclic β-keto esters 1 takes place maintaining the original double-bond geometry. As proposed by the authors, this can be explained through an addition-elimination (Ad_N-E) mechanism. Furthermore, it is shown that also E-alkenes undergo this transformation with retention of configuration of the double bond.