Regio- and stereoselective a(4)-umpolung reactions of alpha,beta-unsaturated esters to 1,6-dicarbonyl compounds by addition of enantiopure nucleophiles to racemic tetracarbonyl(eta(3)-allyl)iron(1+) complexes

The nucleophilic addition of various enantiopure d(2)-carbon nucleophiles (chiral enamines 1 or metalated imines 2 and silylketon derivatives 3) to racemic planar chiral electrophilic tetracarbonyl(eta(3)-allyl)iron(1+) complexes 5 proceeds with complete gamma-regioselectivity and with kinetic resolution of complex 5. Subsequent oxidative demetalation provides access to enantiomerically enriched (ee < 5 - > 92%) 1,6-dicarbonyl compounds 7 in moderate overall yields (14-53%, four steps or 5-21%, five steps) and with retention of the (E)-double bond geometry with respect to the starting material 4.