Enantioselective 1,3-dipolar cycloaddition of nitrile imines to α-substituted and α,β-disubstituted α,β-unsaturated carbonyl substrates:: A method for synthesizing dihydropyrazoles bearing a chiral quaternary center
Enantioselective 1,3-dipolar cycloaddition of nitrile imines to α-substituted and α,β-disubstituted α,β-unsaturated carbonyl substrates:: A method for synthesizing dihydropyrazoles bearing a chiral quaternary center
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DOI：
10.1002/adsc.200600307
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发表时间：
2006-11-01
影响因子：
5.4
通讯作者：
Soeta, Takahiro
中科院分区：
文献类型：
--
作者：
Sibi, Mukund P.;Stanley, Levi M.;Soeta, Takahiro
通过腈亚胺与α-取代-和α,β-二取代-α,β-不饱和羰基底物的对映选择性1,3-偶极环加成反应制备了在5-位带有手性季中心的二氢吡唑。使用 α,β-不饱和羰基底物与 1-苄基-5,5-二甲基吡唑烷-3-酮辅助剂以及 MgI2 和衍生自 (1R,2S)-(+)-cis-1-氨基-2-茚满醇 6 的双恶唑啉配体，经证明是获得具有高对映选择性（高达 99% ee）的手性二氢吡唑的最佳选择。
Dihydropyrazoles bearing a chiral quaternary center at the 5-position have been prepared by enantioselective 1,3-dipolar cycloaddition of nitrile imines to alpha-substituted- and alpha,beta-disubstituted-alpha,beta-unsaturated carbonyl substrates. Use of alpha,beta-unsaturated carbonyl substrates with a 1-benzyl-5,5-dimethylpyrazolidin-3-one auxiliary in conjunction with MgI2, and a bisoxazoline ligand derived from (1R,2S)-(+)-cis-1-amino-2-indanol 6 proved optimal to obtain chiral dihydropyrazoles with high enantio-selectivity (up to 99% ee).