A general synthesis of 2-substituted cyclic 1,3-dienes in two steps from alpha,beta-unsaturated ketones has been developed. Formation of a dien-2-yl triflate followed by a copper(I)-catalyzed cross-coupling reaction with a Grignard reagent gives 2-substituted dienes in fair to excellent yields. Alkyl, aryl, and allyl Grignard reagents can be used.

Abstract:The application of ferrocenyl thiolates as ligands in copper-catalyzed asymmetric substitution reactions of allylic acetates with Grignard reagents is reported. The catalyst formed from lithium thiolate 12 gave the γ-products in high selectivity and with up to 64% ee.Keywords: asymmetric synthesis, copper, ferrocenyl ligands, sulfur, asymmetric catalysis Chiral ferrocenes have received much attention as ligands in transition-metal-catalyzed asymmetric reactions.

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Atom-efficient stoichiometric silylcupration reactions of acetylenes followed by electrophilic trapping of the intermediate vinylcopper species with allylic phosphates have been developed. The reaction sequence was also carried out with the use of a catalytic amount of CuCN employing of both allylic phosphates and allylic phosphinates as electrophiles. The methods developed provide an easy access to silylated 1,4-diene systems.

AbstractÐThe in¯uence of some experimental parameters on the regio-and enantioselectivity in the g-selective substitution reaction of Grignard reagents RMgX with acyclic allylic acetates catalyzed by the arenethiolatocopper(I) complex (S)-1 was studied. When more bulky arenethiolatocopper(I) complexes than (S)-1 were employed in a reaction of allylic acetate 3 with n-BuMgI, the enantioselectivities observed for the g-product were lower. With an arenethiolatocopper(I) catalyst prepared in situ, several Grignard reagents were studied in a substitution reaction with acetate 2. Compared to n-BuMgI, more bulky Grignard reagents gave no improvement of the enantioselectivity in the formation of the g-product. q