Identification of 17-methyl-18-norandrosta-5,13(17-dien-3beta-ol, the C19 fragment formed by adrenal side chain cleavage of a 20-aryl analog of (20S)-20-hydroxycholesterol

Efficient Process Development of Abiraterone Acetate by Employing Design of Experiments

This article describes an efficient process for the synthesis of abiraterone acetate by employing Quality by Design (QbD) principles and statistical design of experiments (DoE). It focuses on the identification of critical quality attributes (CQAs), the relationship between CQAs and material attributes (MAs), and critical process parameters (CPPs) for the synthesis of hydrazone, vinyl iodide intermediates, and final product. Risk assessment is employed to identify the probable critical factors involved in each chemical transformation. The design of experiments approach aided in controlling the formation of critical impurities in all three reactions, namely, deacylated impurity in the hydrazone intermediate, 17-methyl impurity in the vinyl iodide intermediate, and hydroxy and diene impurities in the final API. The process was developed such that we achieved 95, 85, and 82% selectivity and 99, 96, and 99% purity in hydrazone, vinyl iodide intermediate, and final API, respectively. This reflects improved throughput from 25 to 57% as a result of the subtle interplay of critical process parameters identified by DoE studies.