{"title":"Some Issues and Their Solutions in the Process Development of Ethyl 2-(4-Aminophenoxy)thiazole-5-carboxylate: A Key Intermediate of P2X3 Antagonist","authors":"Masahiro Hosoya, Toshikatsu Maki, Takayuki Tsuritani","doi":"10.1021/acs.oprd.5c00015","DOIUrl":null,"url":null,"abstract":"Ethyl 2-(4-aminophenoxy)thiazole-5-carboxylate is a key intermediate of several P2X<sub>3</sub> antagonists required for clinical trials. The synthesis at the early R&D stage delivered this thiazole derivative via a nucleophilic aromatic substitution reaction in highly variable yields, from 7 to 85%. We describe the process development of the initial route of synthesis carefully considering the reaction conditions, process robustness and safety, operational improvement, and the impact on downstream steps. The optimized process was successfully replicated on a multikg scale in a pilot plant, allowing for the supply of the key intermediate in 90% isolated yield with high purity (>99 area%).","PeriodicalId":55,"journal":{"name":"Organic Process Research & Development","volume":"68 1","pages":""},"PeriodicalIF":3.1000,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Organic Process Research & Development","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acs.oprd.5c00015","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, APPLIED","Score":null,"Total":0}
引用次数: 0
Abstract
Ethyl 2-(4-aminophenoxy)thiazole-5-carboxylate is a key intermediate of several P2X3 antagonists required for clinical trials. The synthesis at the early R&D stage delivered this thiazole derivative via a nucleophilic aromatic substitution reaction in highly variable yields, from 7 to 85%. We describe the process development of the initial route of synthesis carefully considering the reaction conditions, process robustness and safety, operational improvement, and the impact on downstream steps. The optimized process was successfully replicated on a multikg scale in a pilot plant, allowing for the supply of the key intermediate in 90% isolated yield with high purity (>99 area%).
期刊介绍:
The journal Organic Process Research & Development serves as a communication tool between industrial chemists and chemists working in universities and research institutes. As such, it reports original work from the broad field of industrial process chemistry but also presents academic results that are relevant, or potentially relevant, to industrial applications. Process chemistry is the science that enables the safe, environmentally benign and ultimately economical manufacturing of organic compounds that are required in larger amounts to help address the needs of society. Consequently, the Journal encompasses every aspect of organic chemistry, including all aspects of catalysis, synthetic methodology development and synthetic strategy exploration, but also includes aspects from analytical and solid-state chemistry and chemical engineering, such as work-up tools,process safety, or flow-chemistry. The goal of development and optimization of chemical reactions and processes is their transfer to a larger scale; original work describing such studies and the actual implementation on scale is highly relevant to the journal. However, studies on new developments from either industry, research institutes or academia that have not yet been demonstrated on scale, but where an industrial utility can be expected and where the study has addressed important prerequisites for a scale-up and has given confidence into the reliability and practicality of the chemistry, also serve the mission of OPR&D as a communication tool between the different contributors to the field.