Ru-Tethered (R,R)-TsDPEN with DMAB as an efficient catalytic system for high enantioselective one-pot synthesis of chiral β-aminol via asymmetric transfer hydrogenation

This work reflects Ru-tethered-TsDPEN as an active chiral catalyst for one pot selective synthesis of optically active alpha-substituted alcohols and its derivatives from alpha-bromo ketones in the presence of dimethylamine borane (DMAB) as the hydrogen source. Various Ru-chiral catalysts have been screened and the methodology proceeded via a (R,R) Ru-tethered TsDPEN catalyst through asymmetric transfer hydrogenation (ATH) of the in-situ formed ketones to the corresponding chiral beta-aminol product. Thus, the Ru-tethered TsDPEN-DMAB catalytic system works efficiently with higher yield and high enantiomeric excess over others for the ATH process. Based on a study of ortho, meta and para substituted alpha-bromo acetophenone derivatives, effective enantioselectivity has been observed for ortho substituted beta-aminol. The mechanism has been optimized depending on product analysis with the help of its kinetic AT-IR study. This work also focusses on the synthesis of various beta-amino alcohol derivatives where the effect of an EWG and EDG on enantio-selectivity has been studied.

Automated summary

The utilization of Ru-tethered-TsDPEN as a chiral catalyst in the presence of DMAB allows for the selective synthesis of optically active alpha-substituted alcohols. This catalytic system shows higher yield and enantiomeric excess compared to others, especially for ortho substituted derivatives.