GB656500A - Improvements in or relating to the preparation of l-arterenol and l-arterenol so prepared - Google Patents

Abstract

l-Arterenol is prepared as a salt in an optically pure form by treating dl-arterenol with d-tartaric acid, l-malic acid or N-benzoyl-l-threonine in the presence of a solvent containing at least 5 per cent of water; the l-form then separates as a hydrated salt while the d-form remains in solution as a more soluble anhydrous salt; the l-salt is purified by fractional crystallization. Treatment of the pure salt with a base, e.g. ammonia, yields the free base. Similarly, d-arterenol yields hydrated salts with l-tartaric acid, d-malic acid and N-benzoyl-d-threonine while l-arterenol gives anhydrous salts with these acids. By alternate use of water and 95 per cent ethanol or methanol, the two forms of arterenol may thus be separated from one another. The d-form may be recemised by treatment with hydrochloric acid and the resolution process repeated to give an increased yield of the l-form. The free base may be converted into other salts, e.g. the hydrochloride, hydrobromide, sulphate, sulphamate, phosphate, tartrate, citrate and succinate. The process is illustrated by an example.