Add time:09/08/2019         Source:sciencedirect.com

Publisher SummaryThis chapter describes the physical properties and synthesis of levarterenol bitartrate. Rotatory dispersion curves indicate the configuration to be D through its relation to D-mandelic acid and D-lactic acid by their negative Cotton effects. The assignments are confirmed through an independent chemical transformation. The synthesis of arterenol (IV) has been reported with utility in large scale preparation. The route employs a phosphorous oxychloride mediated acylation of catechol (I) by α-chloroacetic acid. The crude 4-chloro-acetylcatechol (II) obtained is further reacted with ammonia in alcohol and arterenone (III) is obtained. The purified arterenone is hydrogenated as its hydrochloride salt over palladium on charcoal as catalyst. Racemic arterenol (IV) is obtained by precipitation with ammonia. A similar preparation of dl-arterenol utilizing the protected 3,4-diacetoxy-α-(bromo) acetophenone intermediate has been elaborated in the chapter. The levarterenol d-bitartrate fraction obtained by crystallization is converted to its free base form by precipitation from a methanol solution with ammonia. Repeated precipitations of Z-enriched arterenol from 8-tartrate solutions with ammonia produce levarterenol with the required optical purity. The resolved base is also crystallized as its d-bitartrate salt. Arterenol of lesser optical purity is recovered, racemized with hydrochloric acid, and recycled through the resolution procedure.

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