INDENYL AND FLUORENYL TRANSITION METAL COMPLEXES. VII. INNERSPHERE RICOCHET REARRANGEMENTS ON ALKYLATION OF η5-INDENYL- AND η5-FLUORENYLTRICARBONYLCHROMATE ANIONS

Article abstract of DOI:10.1016/S0022-328X(00)83408-7

Alkylation of K<η⁵-C9H7Cr(CO)3> (Xa) with CH3I and C6H5CH2Br leads to o-alkyl derivatives of η⁵-C9H7Cr(CO)3Alk type.These complexes undergo innersphere ricochet rearrangement, with the alkyl group being shifted to the endo position at C(1) and the chromium tricarbonyl group shifted to the benzene nucleus.The structure of the product of such a rearrangement in the case of η⁵-C9H7(CO)3CrCH2C6H5, i.e. (1-benzyl-3a,4-7,7a-η⁶-indene)chromium tricarbonyl (XVIII), is established by a low temperature X-ray study, indicating an endo position for the benzyl radical.On alkylation of equilibrium tautomeric mixtures of η⁵- and η⁶-fluorenyl-chromium tricarbonyl anions XIa <*> XIb under similar conditions, the η⁵-anion (Xa) yields a ?-alkyl derivative, which is rearranged to (9-endo-alkyl-1-4,4a,9a-η⁶-fluorene)chromium tricarbonyl.Electrophilic attack of the η⁶-anion (XIb) takes place on the outer side at C(9) and leads to a corresponding 9-exo-alkyl derivative.