One-pot organocatalytic domino michael/α-alkylation reactions: Direct catalytic enantioselective cyclopropanation and cyclopentanation reactions

The development of one-pot organocatalytic domino Michael/α- alkylation reactions between bromomalonates or bromoacetoacetate esters and α,β-unsaturated aldehydes is presented. The chiral-amine-catalyzed reactions with bromomalonates as substrates give access to the corresponding 2-formylcyclopropane derivatives in high yields with excellent diastereoselectivity and up to 99% ee. The catalytic domino Michael/α- alkylation reactions between 4-bromo-acetoacetate and enals provide a route for the synthesis of functionalized cyclopentanones in good to high yields with 93-99 % ee. The products from the organocatalytic reactions were also reduced with high diastereoselectivity to the corresponding cyclopropanols and cy-clopentanols, respectively. Moreover, one-pot combinations of amine and heterocyclic carbene catalysis (AHCC) enabled the highly enantioselective synthesis of β-malonate esters (91-97% ee) from the reaction between bromomalonates and enals. The tandem catalysis included the catalytic domino reaction followed by catalytic in situ chemoselective ring-opening of the 2-formylcyclopropane intermediates.