Pentanidium-Catalyzed Enantioselective Phase-Transfer Conjugate Addition Reactions

Ting Ma, Xiao Fu, Choon Wee Kee, Lili Zong, Yuanhang Pan, Kuo-Wei Huang and Choon-Hong Tan

Journal of the American Chemical Society, 2011, 133, 2828–2831. (Highlighted by Synfacts 2011, 5, 0556-0556; contributors: Benjamin List, Saihu Liao)

Abstract: A new chiral entity, pentanidium, has been shown to be an excellent chiral phase-transfer catalyst. The enantioselective Michael addition reactions of tert-butyl glycinate−benzophenone Schiff base with various α,β-unsaturated acceptors provide adducts with high enantioselectivities. A successful gram-scale experiment at a low catalyst loading of 0.05 mol % indicates the potential for practical applications of this methodology. Phosphoglycine ester analogues can also be utilized as the Michael donor, affording enantioenriched α-aminophosphonic acid derivatives and phosphonic analogues of (S)-proline.

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