Industrial methods for the production of optically active intermediates

Enantiomerically pure amino acids, amino alcohols, amines, alcohols, and epoxides play an increasingly important role as intermediates in the pharmaceutical industry and agrochemistry, where both a high degree of purity and large quantities of the compounds are required. The chemical industry has primarily relied upon established chemical methods for the synthesis of these intermediates, but is now turning more and more to enzymatic and biotechnological fermentation processes. For the industrial implementation of many transformations alternative methods are available. The advantages of the individual methods will be discussed herein and exemplified by syntheses of relevant compounds.     

Lipase-mediated deracemization of secondary 1-phenyl-substituted propargylic alcohols of different topology

Acetylation of (±)-1-phenylnon-2-yn-1-ol, (±)-1-phenylhept-1-yn-3-ol, and (±)-1-phenylundec-4-yn-3-ol ((±)-5) in the presence of lipase from Candida cylindracea (CCL) proceeds slowly to give products with ee 20%. The acetates of these alcohols are hydrolyzed in the presence of porcine pancreatic lipase (PPL) equally unsatisfactorily. The (⁶-arene)tricarbonylchromium complex of alcohol (±)-5 is acetylated in the presence of CCL up to 22% conversion to give (R)-acetate whose oxidative decomplexation followed by saponification results in alcohol (R)-(–)-5 with ee 95%. The configuration of alcohols (–)-5 and (+)-5 was determined by NMR spectroscopy of their esters with (R)- and (S)-Mosher"s acids.