Biocatalytic Oxidation of 2-Methylquinoxaline to 2-Quinoxalinecarboxylic Acid

Abstract

A microbial process using the fungus Absidia repens ATCC 14849 is described for the oxidation of 2-methylquinoxaline to 2-quinoxalinecarboxylic acid. A campaign consisting of three 14000-L runs produced 20.5 kg of the acid with a 28% overall yield. The bioconversion gave a lower yield compared with a three step chemical synthesis (35%), but was carried out in one pot, and avoided safety issues with a di-N-oxide intermediate. Although successfully scaled to produce kilograms of 2-quinoxalinecarboxylic acid for synthesis of a drug candidate, the A. repens bioconversion is unsuitable for further scale-up due to low product concentration (∼1 g/L). A second microbial process using Pseudomonas putida ATCC 33015 is also described for the oxidation of 2-methylquinoxaline. The P. putida bioconversion gave an 86% in situ yield at 8-L scale and yielded a product concentration approximately 10-fold greater than that of the A. repens bioconversion.

Understanding and Improving NADPH‐Dependent Reactions by Nongrowing Escherichia coli Cells

“…In their very useful summary of fine chemicals that have been produced commercially in biotransformations, Straathof et al listed data for three enzymatic oxidations, all of which employed whole cells (3). One of these examples, the oxidation of N ‐butylglucamine by nongrowing Gluconobacter oxid ans cells reported by Landis et al (43) was exceptionally efficient compared to the other two, which are more typical for this type of bioconversion (space−time yields of 0.003 and 0.002 g/L·h and final product titers of 1.0 and 0.4 g/L, respectively) (44, 45). We carried out the Baeyer−Villiger oxidation of cyclohexanone with a space‐time yield of 0.38 g/L·h to afford 9.1 g/L product using a biocatalyst:substrate ratio (g/g) of 0.63.…”

Industrial biotechnology—the future of green chemistry?

“…The preparation of 2-quinoxalinecarboxylic acid 19, a precursor of numerous biologically active compounds like the 4-aminoazepan-3-one protease inhibitor of Smith Kline or the new metabotropic glutamate receptor compounds of AstraZeneca, NPS Pharmaceuticals and others, 127,128 is done by a three step, multi-enzyme process (Scheme 9). 129 The development of this process was driven by the unsuitability of the former chemical process due to safety issues and low yields within the production process. After screening different microorganisms for the first scale up, the fungus Absidia repens ATCC 14849 was chosen.…”

“…Thereby, a controlled addition of substrate and benzyl alcohol as inducer and carbon source are decisive in achieving a high product concentration (maximum 10.7 g L -1 ) and a high yielding process (86% bioconversion yield) that is commercially feasible after further improvement and scale up. 129 In the same year of successful scale up, the process was patented by Pfizer. 130 Artemisinin, a secondary plant compound, is the key-player of artemisinin-based combination therapies (ACTs) used for antimalarial treatment.…”

Biotransformations in Small‐Molecule Pharmaceutical Development

“…34 For a manufacturing-scale process the requirement to maximize overall yield and eliminate side reactions is greater still, yet whole-cell biocatalysis remains the sole option for oxidative biotransformation. For example, a whole-cell monooxygenase-based oxidation of 2-methylquinoxaline has been reported by Wong et al 36 that uses a strain of Pseudomonas putida possessing an aryl ADH and a benzaldehyde dehydrogenase that together generate 2-quinoxaline carboxylic acid in three steps at a reported 86 % overall yield (Scheme 1.5).…”