Regio- and stereoselective a 4-umpolung reactions of α,β-unsaturated esters to 1,6-dicarbonyl compounds by addition of enantiopure nucleophiles to racemic tetracarbonyl ( η3-alyl)iron(1+) complexes

Abstract

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( η 3-allyl)iron(1+) complexes 5 proceeds with complete γ-radioselectivity and with kinetic resolution of complex 5. Subsequent oxidative demetalation provides access to enantiometrically 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.