Reactions of “in‐Situ” Generated Cr(CO)₅CN–C(Cl)–PR₃ (R = Ph, NMe₂) with Potential Dipolarophiles. New Examples of [3+2] Cycloadditions with Concomitant Interligand CC Bond Formation [1]

Abstract

The highly functional chromio nitrile ylides Cr(CO)5C≡N–C(Cl)–PR3 (R = Ph, NMe2) (2a, b) form readily in mixtures of Cr(CO)5CNCCl3 (1) with the respective phosphanes. Their reactions without isolation with the acylating agent Cr(CO)5CN(C=O)Ar (Ar = C6H4‐p‐NO2), MeO2CC≡CCO2Me, ketones (R2C=O, R = Me, Et; 2R = 9‐fluorenediyl) and phenyl isocyanate to give the Cl/COAr‐substitution‐ (6a), alkyne insertion‐ (10) and [3+2] cycloaddition products (13, 14) are described. Formation of the latter is accompanied by an interligand CC coupling with loss of P(NMe2)3 and OP(NMe2)3 (after hydrolysis). Their reactions are compared with those of the parent compounds LnMCN–C(H)–PPh3.