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Short Paper | Regular issue | Vol 92, No. 4, 2016, pp.720-732
Published online, 1st February, 2016
DOI: 10.3987/COM-16-13408
■ Synthesis of a New Chiral C2-Symmetric NHC-AuCl Complex

Naoya Okitsu, Takuya Yoshida, Kensuke Usui, and Masahisa Nakada*

*Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan

Abstract

A New chiral C2 symmetric NHC ligand with two binaphthyl units has been synthesized. The new NHC ligand features two seven-membered rings that link the imidazolylidene with the binaphthyl units. X-Ray crystallographic analysis of the new NHC-AuCl complex indicates that the Au-Cl bond is located between the phenyl groups of the binaphthyl units and suggests that this arrangement could induce enantioselectivity in reactions. Indeed, catalytic asymmetric ene-yne cyclization of 2b in the presence of a catalytic amount (5 mol%) of cationic complex of 13 quantitatively afforded the cyclized product with 78% ee.