Enantioselective total synthesis of (S)-(+)-lennoxamine through asymmetric hydrogenation mediated by l-proline-tetrazole ruthenium catalyst

A novel asymmetric synthetic strategy to prepare isoindolobenzazepine based lennoxamine alkaloid has been achieved in high ee% starting from 2-(benzo[d][1,3]dioxol-5-yl)ethanamine and 1-(chloromethyl)-2,3-dimethoxybenzene in 5 steps and with a 34% overall yield. The potentiality of this route involved the Bischler-Napieralsky cyclization that leads to tetracyclic indolinium skeleton, generation of chiral center through asymmetric hydrogen-transfer reaction employing l-proline-tetrazole as chiral ligand with Ru/Ir/Rh, and anodic oxidation as the key steps in the synthesis.     

Stereoselective bioreduction of β-carboline imines through cell-free extracts from earthworms (Eisenia foetida)

Although remarkable advances have been made over the last decade in organic synthesis, catalysis, and biotechnology, there is still a need to introduce and develop new processes for chemical production to achieve sustainable and cleaner approaches to support the increasing global pharmaceutical/chemical industry. There is a growing need to produce optically active compounds in high yields to maintain and support areas such as pharmaceutical and natural product synthesis. Thus, chemists today are looking for alternative reactions carried out under green conditions. In this context, we describe β-carboline imine reductions employing cell-free extracts from red Californian earthworms (Eisenia foetida) in high yields and enantiomeric excesses. The enantiomeric excess values of the bioreduction showed no dependence on the imine 1a–g substituents to afford amines with an (R)-configuration. Based on these data, a model for the cell-free extract from the earthworm is proposed.