Sub Topic | Secondary Topic: Analytical Methodology - Non-biological Matrix | HPLC (Small Molecule)
Authors: Vera Leshchinskaya, Bristol-Myers Squibb Company (Main Author, Presenting Author); Jana Casey, Bristol-Myers Squibb Company; Neil Strotman, Bristol-Myers Squibb Company; Pang Geng, Bristol-Myers Squibb Company; Yichen Tan, Bristol-Myers Squibb Company
Presenting Author: Vera Leshchinskaya
Purpose: During the course of development for a BMS compound, an improvement to the yield of one of the early intermediates was desired due to expensive starting materials (SM). This would not only reduce the cost of the entire synthesis but also increase the throughput.
Methods: In-process monitoring of the reaction completion was challenging due to the lack of chromophore and highly polar nature of starting material 1 (SM1). Systematic analysis of in-process reaction samples using a generic HPLC method with a universal detector (Corona Charged Aerosol Detector) showed the reaction ”stalled” with ~80% yield, regardless of process conditions, as both starting materials were not completely consumed. Using a software-assisted LC/MS peak co-elution check (ACD Autochrom), the source of the low yield was identified as an unexpected methyl transfer to the piperidine nitrogen of SM1 from the methyl ester of starting material 2 (SM2). Both methylated and dimethylated SM1 eluted as one peak on the generic HPLC method. Subsequently, a quantitative CAD method that employed a mixed-mode chromatography column (PRIMESEP A, Sielc Technology) was rapidly developed and used for in-process monitoring.
Results: The product, starting material SM1 (limiting reagent) and their derivatives were baseline separated within 10 min enabling quick process development and optimization. Based on this finding, the reaction yield was vastly improved by altering the original starting material to an ethyl ester of SM2, eliminating the undesired SN1 alkylation.
Conclusion: The initial 80% yield was improved to 94% with a mechanistic understanding of the reaction due to the investigation.
See attached abstract pdf for images.