Efficient Synthesis of the Nucleus of Atorvastatin Calcium

Abstract

An efficient synthetic route for the parent nucleus of atorvastatin calcium was successfully established through the modification of the related reactions. Under the optimized conditions, compound 1 was obtained in 61.2% yield (lit. 51.4%) from methyl isopropyl ketone via five steps. Two impurities generated by the aldol condensation of methyl isopropyl ketone were identified by gas chromatography–mass spectrometry and their generation can be inhibited by reducing the mixing time of methyl isopropyl ketone and NaH. One oxybromination protocol with hydrogen peroxide was employed to make the best of bromine. A debromination by-product was isolated and confirmed by ¹H NMR, ¹³C NMR, and high-resolution mass spectrometry and its generation mechanism was discussed. The impurity can be inhibited by protecting the reaction from light and easily removed by recrystallization.

GRAPHICAL ABSTRACT

Keywords:

• Atorvastatin calcium
• parent nucleus
• reaction mechanism
• synthesis