Approaches to selective isoprenologation via reactions of (η3-allyl)Fe(CO)4+ with allyl nucleophiles

Article abstract of DOI:10.1016/0022-328X(91)80086-Y

The reactions of substituted (η³-allyl)Fe(CO)4BF4 complexes 1 with various allyl-metals and dienolate derivatives have been investigated in search of a method for regio- and stereocontrolled allyl-allyl coupling.All three classes of allyl derivatives react with 1 in moderate to good yield with variable regioselectivity; the silyl derivatives 2 generally provide good regioselectivity for attack at the less substituted terminus of unsymmetrical derivatives of 1 but deprotonation of the 1,1-dimethylallyl complex 1e prevents efficient isoprenylation.Although deprotonation of 1e also dominates with the siloxydienes, the lithium dienolates couple efficiently with 1; however, reaction at the α position of the dienolate dominates.