Salicylato titanocene complexes as cooperative organometallic Lewis acid and Brønsted acid catalysts for three-component mannich reactions

Ya Wu; Chun Chen; Gai Jia; Xuyang Zhu; Huaming Sun; Guofang Zhang; Weiqiang Zhang; Ziwei Gao

doi:10.1002/chem.201402438

Salicylato titanocene complexes as cooperative organometallic Lewis acid and Brønsted acid catalysts for three-component mannich reactions

Chemistry. 2014 Jul 7;20(28):8530-5. doi: 10.1002/chem.201402438. Epub 2014 Jun 20.

Authors

Ya Wu¹, Chun Chen, Gai Jia, Xuyang Zhu, Huaming Sun, Guofang Zhang, Weiqiang Zhang, Ziwei Gao

Affiliation

¹ Key Laboratory of Applied Surface and Colloid Chemistry, MOE, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062 (P.R. China), Fax: (+86) 29-81530727.

PMID: 24954651
DOI: 10.1002/chem.201402438

Abstract

A binary acid system has been developed that features an air-stable organometallic precursor, titanocene dichloride, and simple organic cooperative Brønsted 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 (1) H 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.

Keywords: Brønsted acids; CC coupling; cooperative catalysis; organometallic Lewis acid; salicylic acid.