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Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and ?,?-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives.

ABSTRACT: The catalytic synthesis of nitrogen-containing heterocycles is of great importance to medicinal and synthetic chemists, and also a challenge for modern chemical methodology. In this paper, we report the synthesis of pyrazolidine derivatives through a domino aza-Michael/hemiacetal sequence with chiral or achiral secondary amines as organocatalysts. Thus, a series of achiral pyrazolidine derivatives were obtained with good yields (up to 90%) and high diastereoselectivities (>20:1) with pyrrolidine as an organocatalyst, and enantioenriched pyrazolidines are also achieved with good results (up to 86% yield, >10/1 regioselectivity, >20:1 dr, 99% ee) in the presence of (S)-diphenylprolinol trimethylsilyl ether catalyst.

SUBMITTER: Geng ZC

PROVIDER: S-EPMC3511004 | biostudies-other | 2012

REPOSITORIES: biostudies-other

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Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives.

Geng Zhi-Cong ZC Chen Jian J Li Ning N Huang Xiao-Fei XF Zhang Yong Y Zhang Ya-Wen YW Wang Xing-Wang XW

Beilstein journal of organic chemistry 20121009

The catalytic synthesis of nitrogen-containing heterocycles is of great importance to medicinal and synthetic chemists, and also a challenge for modern chemical methodology. In this paper, we report the synthesis of pyrazolidine derivatives through a domino aza-Michael/hemiacetal sequence with chiral or achiral secondary amines as organocatalysts. Thus, a series of achiral pyrazolidine derivatives were obtained with good yields (up to 90%) and high diastereoselectivities (>20:1) with pyrrolidine ...[more]

PMID: 23209504

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