TfNH2 as achiral hydrogen-bond donor additive to enhance the selectivity of a transition metal catalyzed reaction. Highly enantio- and diastereoselective rhodium-catalyzed cyclopropanation of alkenes using alpha-cyano diazoacetamide.
A highly stereoselective (up to 98% ee and 99:1 dr) Rh(II)-catalyzed formation of nitrile-substituted cyclopropanes is described. Alpha-cyano diazoacetamide reagents react with a variety of mono- and disubstituted olefins in good yields and excellent enantio- and diastereocontrol. Less reactive substrates, such as aliphatic olefins, also undergo the reaction. This new methodology features the unprecedented use of an achiral hydrogen-bond donor additive to enhance the selectivity and exploits the powerful trans-directing ability of amides solving the diastereocontrol issue of the formation of substituted 1-cyanocyclopropane-1-carboxy derivatives.
Marcoux
David
D
Departement de Chimie, Université de Montréal, P.O. Box 6128, Station Downtown, Montréal (Québec), Canada H3C 3J7.
Azzi
Soula
S
Charette
André B
AB