Unusual anti-selectivity was observed in the conjugate addition of aldehydes to nitroalkenes, when a biphenyl-based chiralsecondaryamine was used as catalyst.
当使用联苯基手性仲胺作为催化剂时,在醛与硝基烯烃的共轭加成中观察到了异常的抗选择性。
Silylated Pyrrolidines as Catalysts for Asymmetric Michael Additions of Aldehydes to Nitroolefins
Silicon can! A convenient synthesis of enantiopure (S)‐2‐(diphenylmethylsilyl)pyrrolidine is described and its organocatalytic activity in asymmetricMichael reactions is demonstrated (see scheme). By using 10 mol % of this novel organocatalyst, the addition of aldehydes to nitroolefins affords products with high stereoselectivities (d.r. ≤97:3 and e.r. ≤95:5) in yields up to 99 %.
Silyl Fluoride Electrophiles for the Enantioselective Synthesis of Silylated Pyrrolidine Catalysts
作者:Kaleb I. Jentzsch、Taewoo Min、Jennifer I. Etcheson、James C. Fettinger、Annaliese K. Franz
DOI:10.1021/jo200991q
日期:2011.9.2
Chiral silylated pyrrolidine catalysts are obtained in high yield and enantioselectivity by sparteine-mediated lithiation of N-Boc-pyrrolidine and addition to silyl fluoride electrophiles. The activity and enantioselectivity of a new tert-butyldiphenylsilylpyrrolidine catalyst has been demonstrated for various asymmetric Michael reactions at 5 mol % catalyst loading and affords up to 99% ee for asymmetric