Reactions of (η5-C5H5)(CO)2Fe-substituted N-sulfonyl azadienes with C-nucleophiles. A route to 5-substituted dihydropyrrolones

Article abstract of DOI:10.1021/om000235j

A variety of cyclic β-[(η⁵-C₅H₅)(CO)₂Fe]-substituted N-sulfonyl azadienes 4 were prepared: e.g., from the corresponding iron-substituted (Z)-enals and benzenesulfonamide. Reactions of these iron compounds with Grignard reagents or organolithiums gave 5-substituted α,β-unsaturated N-sulfonyl γ-lactams 5. In some cases the corresponding non-N-protected 5-substituted γ-lactams 6 were isolated as well. Key steps of these reaction cascades are the initial 1,2-addition to the imine moiety and the subsequent carbonylation step. The reaction of the chromene-iron complex 4e with (allyl)MgCl gave the (η³-allyl)-iron-γ-lactam complex 8a with a ring-opened chromene framework. This complex was structurally characterized by X-ray analysis.