Silyl Nitronate Cycloadditions Catalyzed by Cu(II)-Bisoxazoline
摘要:
Cu(OTf)(2) and chiral BOX ligand-catalyzed 1,3-dipolar cydoadditions Of triisopropylsilyl nitronates with alpha,beta-unsaturated carboximides produced chiral isoxazolines in high yields, high enantioselectivities, and complete diastereoselectivities. These chiral isoxazoline products were further converted into structurally diversified derivatives, which demonstrated the utility of the new method of constructing isoxazolines. The transition-state structure of cydoaddition was proposed in the light of the relative and absolute configurations of the products.