Silyl Nitronate Cycloadditions Catalyzed by Cu(II)-Bisoxazoline

Cu­(OTf)2 and chiral BOX ligand-catalyzed 1,3-dipolar
cycloadditions of triisopropylsilyl nitronates with α,β-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 cycloaddition was proposed in the
light of the relative and absolute configurations of the products.

Cu(OTf)2与手性BOX配体催化的1,3-偶极环加成反应，将三异丙基硅基硝酸盐与α,β-不饱和羧亚胺相结合，高效地制备了手性异噁唑啉，并展现出高对映选择性和完全的立体选择性。这些手性异噁唑啉产物随后被转化为结构多样化的衍生物，彰显了构建异噁唑啉的新方法的应用价值。基于产物的相对和绝对构型，提出了环加成反应的过渡态结构。