Bis(2-aminobenzoimidazole)-Organocatalyzed Asymmetric Alkylation of Activated Methylene Compounds with Benzylic and Allylic Alcohols

The first organocatalyzed asymmetric alkylation of activated methylene compounds using benzylic and allylic alcohols as alkylating agents through dual hydrogen bond activation in an SN1-type reaction is reported. This green protocol employs a bis(2-aminobenzoimidazole) in combination with an achiral Brønsted acid as a bifunctional catalytic system and gives the alkylation products with moderate to good enantioselectivities. Although the scope of the reaction is limited, this methodology can be considered as complementary to existing metal-catalyzed processes. In addition, modest results were obtained in a first attempt to perform a metal-free asymmetric Tsuji–Trost reaction using allylic alcohols. Finally, the recovery and reusability of the organocatalyst is also achieved.

Spanish Ministerio de Ciencia e Innovación (MICINN) (projects CTQ2010-20387 and Consolider Ingenio 2010, CSD2007-00006), FEDER, the Generalitat Valenciana (PROMETEO 2009/039) and the University of Alicante are gratefully acknowledged for financial support. A.B. would also like to thank University of Alicante (Project GRE12-03).