Salicylato titanocene complexes as cooperative organometallic lewis acid and bronsted acid catalysts for three-component mannich reactions

Article abstract of DOI:10.1002/chem.201402438

A binary acid system has been developed that features an air-stable organometallic precursor, titanocene dichloride, and simple organic cooperative Bronsted acids, which allowed for mild and highly efficient Mannich reactions of both aryl and alkyl ketones with excellent yields and satisfactory diastereoselectivity. Mechanistic studies, including ¹H NMR titration, X-ray structure analyses as well as isolation of catalytically active species, elucidated the dramatic synergistic effects of this new binary acid system.