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Synfacts 2010(7): 0826-0826  
DOI: 10.1055/s-0029-1220124
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

An Organocatalytic Approach to ;Spiro-3,4-dihydropyrans

Contributor(s): Benjamin List, Olga Lifchits
W. Yao, L. Pan, Y. Wu, C. Ma*
Zhejiang University, Hangzhou, P. R. of China
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Publication History

Publication Date:
22 June 2010 (online)

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Significance

Ma and colleagues report the use of a cinchona alkaloid dimer 3 as a Brønsted base catalyst in the spiroannulation of cyclic β-keto ­aldehydes 1 and unsaturated α-keto esters 2. The resulting spiro-3,4-dihydropyrans 4 were obtained with a wide scope and good to excellent yields and enantioselectivities. The reaction is reasoned to proceed via an enantioselective Michael addition followed by a diastereoselective hemiacetali­zation.