Versatile, diastereoselective additions of silyl ketene acetals, allyl tributylstannane, and Me3SiCN to N-acyl pyrazolines:: Asymmetric synthesis of densely functionalized pyrazolidines

[GRAPHICS] We report the diastereoselective addition of a wide range of nucleophiles to chiral pyrazolines to provide facile access to a range of useful densely functionalized building blocks for asymmetric synthesis. Coupled with the asymmetric cycloaddition reaction of Me3SiCHN2 to chiral acrylates, access to these chiral heterocycles is considerably expanded.