Controlled Functionalization in the Cyclopentane Ring Using Organomolybdenum Chemistry

Article abstract of DOI:10.1021/jo00225a056

The synthesis and reactivity of a series of η³-cycloheptenyl-Mo(CO)2Cp and η⁴-cycloheptadiene-Mo(CO2)2Cp complexes are reported.The parent ?-allyl complex (η³-C7H11)Mo(CO)2Cp undergoes hydride abstraction on treatment with Ph3CPF6 to give (η⁴-C7H10)Mo(CO)2Cp cation as the PF6^- salt.This complex reacts stereospecifically with a variety of carbon nucleophiles, including Grignard reagents and stabilized enolates, by addition to the diene ligand to give substituted ?-allyl complexes (η³-C7H10R)Mo(CO)2Cp.With the unsymmetrical enolate from methyl 2-oxocyclopentanecarboxylate a high degree of diastereoselectivity is observed.Alkyl-substituted complexes, (η³-C7H10R)Mo(CO)2Cp (R = CH3, CH2CH=CH2, C6H4OMe-p), undergo regiospecific hydride abstraction to give (η⁴-C7H9R)Mo(CO)2Cp cations which react with a range of nucleophiles stereospecifically at the diene ligand.The regioselectivity of this second nucleophile addition was studied.Decomplexation of the product ?-allyl complexes by a cyclofunctionalization / demetalation procedure is reported.