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Synfacts 2007(10): 1025-1025  
DOI: 10.1055/s-2007-968980
Synthesis of Heterocycles
© Georg Thieme Verlag Stuttgart · New York

Copper-Catalyzed Asymmetric Synthesis of Dihydropyridines

Contributor(s):Victor Snieckus, Wei Gan
Z. Sun, S. Yu, Z. Ding, D. Ma*
Shanghai Institute of Organic Chemistry, P. R. of China
Enantioselective Addition of Activated Terminal Alkynes to 1-Acylpyridinium Salts Catalyzed by Cu-Bis(oxazoline) Complexes
J. Am. Chem. Soc.  2007,  129:  9300-9301  
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Publication History

Publication Date:
07 November 2007 (online)

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Key words

dihydropyridines - asymmetric synthesis - piperidines - indolizidine 167B - indolizidine 223AB

Significance

A Cu-bisoxazoline catalyzed enantio­selective addition of terminal alkynes to N-acylpyridinum salts is reported. The reaction is quite general, proceeds in good yields and poor to excellent ee without 1,4-addition products observed. A carbonyl functionality at the 3-position of terminal alkynes is essential for achieving high enantioinduction. The dihydropyridine products were further converted into 2,6-cis-disubstituted piperidines.

Comment

Piperidines are components of several classes of alkaloids and are prevalent substructures of bioactive molecules (see review below). Previous stereoselective syntheses of dihydro­pyridines by asymmetric nucleophilic attack onto activated N-acylpyridiniums (D. L. Comins and coworkers J. Am. Chem. Soc. 1999, 121, 2615; C. Marazano and co-workers J. Org. Chem. 1993, 53, 2052) mostly involve the use of chiral pyridine substrates. The present catalytic methodology has the advantage of using readily available starting materials. The utility of this method was demonstrated by the efficient syntheses of the two indolizidines 167B and 223AB.

Review

P. M. Weintraub and co-workers Tetrahedron 2003, 59, 2953.

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