Michael addition of chiral formaldehyde N,N-dialkylhydrazones to activated cyclic alkenes

14 páginas, 1 figura, 2 tablas, 15 esquemas.The nucleophilic conjugate addition of chiral formaldehyde N,N-dialkylhydrazones 1 to doubly activated cyclic alkenes 2–8 proceeds smoothly to afford the corresponding Michael adducts 14, 16, 18, 20, 22, 24, and 25 in variable yields and selectivities. The reactions take place either spontaneously or in the presence of MgI2 as a mild Lewis acid depending on the type of substrate. Release of the chiral auxiliary was achieved by transformation of the hydrazone moiety into acetals, dithioacetals or nitriles.We thank the Spanish ‘Ministerio de Ciencia y Tecnología’ (Grant BQU2001-2376, predoctoral fellowship to A.P., and ‘Ramon y Cajal’ grant to E.D.), the European Commission (HPRN-CT-2001-00172 and HPMT-CT-2001-00248) and the ‘Junta de Andalucía’ for financial support.Peer reviewe