A Method for the Racemization of 2-Methylpyrrolidine: A Histamine H₃ Receptor Pharmacophore

Abstract

This paper describes a method for the racemization of unwanted (S)-1 isomer arising from the resolution of (±)-1. The process of racemization involves thiyl radical-mediated reversible hydrogen abstraction at the chiral center, in the presence of AIBN in water. The racemized isomer was subsequently resolved by L-(+)-tartaric acid to get (R)-1, a histamine H 3 receptor pharmacophore. We foresee that such an approach of racemization will be industrially useful for recycling waste (S)-1 enantiomer.

Stereochemical Editing via Coupled Epimerization and Optical Resolution to Sustainably Manufacture a Key Adagrasib Building Block

“…Various methods of epimerization were considered via a standard retrosynthetic analysis. This included the transfer dehydrogenation systems previously described , and hydrogen atom abstraction promoted by photochemical or thermal radical initiators . The presence of the two benzyl groups complicated these approaches, since the benzylic positions would be expected to react first.…”

Integration of ion exchange resin materials for a downstream‐processing approach of an imine reductase‐catalyzed reaction

“…In addition, in situ-product removal techniques, such as crystallization or membranes would be also a powerful addition, but are currently not widely applicable for IREDcatalyzed reaction systems. 45,46 This study aims at presenting the utilization of ion exchange resins as an easy option to perform the product isolation from IRED-catalyzed reaction systems, including its potential usage on a preparative scale. A small selection of ion exchange materials was mentioned in the past within biocatalytic processes, but their applications are still somehow limited with a few noticeable exceptions.…”

“…Alternative nonconventional reaction media, such as ionic liquids, 37‐39 deep eutectic solvents, 40,41 and others, 42‐44 could be used to simplify the product isolation but may suffer from major drawbacks like activity losses of the biocatalyst and a high complexity associated with a cost‐intensive system. In addition, in situ‐product removal techniques, such as crystallization or membranes would be also a powerful addition, but are currently not widely applicable for IRED‐catalyzed reaction systems 45,46 …”