Evaluation of 3,3'-Triazolyl Biisoquinoline ,'-Dioxide Catalysts for Asymmetric Hydrosilylation of Hydrazones with Trichlorosilane.

A new class of axial-chiral biisoquinoline ,'-dioxides was evaluated as catalysts for the enantioselective hydrosilylation of acyl hydrazones with trichlorosilane. While these catalysts provided poor to moderate reactivity and enantioselectivity, this study represents the first example of the organocatalytic asymmetric reduction of acyl hydrazones. In addition, the structures and energies of two possible diastereomeric catalyst-trichlorosilane complexes (-HSiCl) were analyzed using density functional theory calculations.

Asymmetric Catalytic Ketimine Mannich Reactions and Related Transformations.

The catalytic enantioselective ketimine Mannich and its related reactions provide direct access to chiral building blocks bearing an α-tertiary amine stereogenic center, a ubiquitous structural motif in nature. Although ketimines are often viewed as challenging electrophiles, various approaches/strategies to circumvent or overcome the adverse properties of ketimines have been developed for these transformations. This review showcases the selected examples that highlight the benefits and utilities of various ketimines and remaining challenges associated with them in the context of Mannich, allylation, and aza-Morita-Baylis-Hillman reactions as well as their variants.