Reversible addition of carbon nucleophiles to some nitrogen-substituted η6-arenetricarbonylchromium(0) compounds

Article abstract of DOI:10.1016/0022-328X(88)80359-0

A study has been made of the nucleophilic addition/oxidation reactions of η⁶-1-methyl-1,2,3,4-tetrahydroquinolinetricarbonylchromium(0) (1), η⁶-1-methylindolinetricarbonylchromium(0) (2), and η⁶-2-N,N-dimethylaminotoluenetricarbonylchromium(0) (3) with the nucleophiles 2-lithio-2-methyl-propionitrile (A), 2-lithio-acetonitrile (B) and 2-lithio-2-methyl-1,3-dithiane (C).The regioselectivity in the addition of stabilized nucleophiles is time- and temperature-dependent, indicating the onset of thermodynamic control in prolonged/high temperature reactions.The addition is reversible, as indicated by crossover experiments with benzene-Cr(CO)3, the rate for dissociation of the C-C bond being strongly dependent on both the structure of the intermediate η⁵-cyclohexadienyltricarbonylchromium anions as well as the structure of the nucleophile.The regioselectivity of the addition/oxidation reaction can be optimized by an appropriate choice of reaction for each of the compounds 1, 2 and 3.