TY - JOUR A1 - Geng, Zhi-Cong A1 - Chen, Jian A1 - Li, Ning A1 - Huang, Xiao-Fei A1 - Zhang, Yong A1 - Zhang, Ya-Wen A1 - Wang, Xing-Wang T1 - Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives JF - Beilstein Journal of Organic Chemistry PY - 2012/// VL - 8 SP - 1710 EP - 1720 SN - 1860-5397 DO - 10.3762/bjoc.8.195 PB - Beilstein-Institut JA - Beilstein J. Org. Chem. UR - https://doi.org/10.3762/bjoc.8.195 KW - aza-Michael KW - domino KW - hydrazine KW - organocatalysis KW - pyrazolidine N2 - 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. ER -