An Entry to a Chiral Dihydropyrazole Scaffold: Enantioselective [3 + 2] Cycloaddition of Nitrile Imines
摘要:
We have developed a versatile strategy to access dihydropyrazoles in highly enantioenriched form. Dipolar cycloaddition of electron-deficient acceptors and in situ-generated nitrile imines proceeds with high regio- and enantioselectivity using 10 mol % chiral Lewis acid catalyst. A variety of dihydropyrazoles that incorporate functionality for further manipulation have been prepared.
An Entry to a Chiral Dihydropyrazole Scaffold: Enantioselective [3 + 2] Cycloaddition of Nitrile Imines
摘要:
We have developed a versatile strategy to access dihydropyrazoles in highly enantioenriched form. Dipolar cycloaddition of electron-deficient acceptors and in situ-generated nitrile imines proceeds with high regio- and enantioselectivity using 10 mol % chiral Lewis acid catalyst. A variety of dihydropyrazoles that incorporate functionality for further manipulation have been prepared.
Dual Activation of Unsaturated Amides with Schwartz's Reagent: A Diastereoselective Access to Cyclopentanols and N,O‐Dimethylcyclopentylhydroxylamines.
The concomitant generation of a nucleophilic and an electrophilic site from unsaturated Weinreb amide by using Cp2Zr(H)Cl) as the unique reagent was developed to promote a cyclisation reaction. The access to trans-2-substituted cyclopentanols or cyclopentylhydroxylamines can be selectively driven by a judicious choice of the cyclisationpromotor. An access to cis-3-substituted is also described.