Designing new readily available sugar-based ligands for asymmetric transfer hydrogenation of ketones. In the quest to expand the substrate scope

Abstract

Asymmetric transfer hydrogenation (ATH) has emerged as one of the most effective and sustainable synthetic tool for synthesizing enantiopure alcohols. Since Noyori’s group successfully applied Ru-catalysts modified with chiral β-amino alcohols or diamines as ligands, a large number of catalytic systems has been successfully developed. However, further improvement in terms of substrate scope, selectivity, and turnover frequency are required to make the process competitive with conventional hydrogenations. Overcoming these limitations requires research toward the design of new ligands. Such a task becomes easier if readily modulable chiral ligands are at hand. Sugar-based ligands are particularly useful for addressing this need. They are readily available, highly functionalized, and their modular constructions are easy. Series of chiral ligands can be screened in the search for high activities and selectivities for each type of substrate. This digest paper will discuss the progress on the use of sugar-based ligands in ATH reactions.