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Communication | Regular issue | Vol 78, No. 5, 2009, pp.1171-1176
Published online, 9th January, 2009
DOI: 10.3987/COM-08-11604
■ Cyclo[-His-His-] Derived C2-Symmetric Diketopiperazine as Chiral Ligand for Asymmetric Diels-Alder Reactions

Masahiro Furutani, Seiji Sakamoto, and Kazuaki Kudo*

*Institute of Industrial Science, The University of Tokyo, Komaba, Meguro-ku, Tokyo 153-8505, Japan

Abstract

A cyclic dipeptide based chiral ligand, cyclo[-His(Tr)-His(Tr)-] (Tr = triphenylmethyl), was designed and prepared through bis-N(τ)-tritylation of two imidazole rings of cyclo[-His-His-]. The complex prepared in situ by mixing Cu(OTf)2 with equimolar amount of this ligand successfully catalyzed asymmetric Diels-Alder reactions in fair to good yields and moderate selectivities.