952198-17-3Relevant academic research and scientific papers
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
Sibi, Mukund P.,Stanley, Levi M.,Soeta, Takahiro
, p. 2371 - 2375 (2007/10/03)
Dihydropyrazoles bearing a chiral quaternary center at the 5-position have been prepared by enantioselective 1,3-dipolar cycloaddition of nitrile imines to α-substituted- and α,β-disubstituted-α,β- unsaturated carbonyl substrates. Use of α,β-unsaturated carbonyl substrates with a l-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).
