Amides microbial hydroxylation

Although much of the work on the microbial hydroxylation of amides has been directed at active-site m ing of the enzyme responsible, the products themselves are valuable building blocks for further synthesis, for example, for various optically active sesquiteipenes or -lactams. In this latter context regioselective hydroxylation of unactivated positions is particularly attractive as several -lactam antibiotics, e.g. the carbapenem derivative thienamycin, have a free hydroxy group in their structure. 

In some cases the regioselectivity of a microbial oxidation is governed by the absolute configuration of the substrate. For example, the racemic amide (13 Scheme 4) gives two major products upon culturing with Beauveria sulfurescens, one from hydroxylation at C-S (14 29% yield, 44% ee) and derived from the (15)-enantiomer of the substrate, and one from hydroxylation at C-4 (IS 22% yield, 53% ee) and derived from the (l/f)-enantiomer. ... 

An acylation reaction occurs on the amine terminal functions and, possibly, on some side groups (e.g., the hydroxyls) and thus leaves the carboxyl groups free, which must be neutralized. Because these surfactants contain amide functions, they are sensitive to hydrolysis. Also, they are prone to microbial degradation if they are contaminated and not appropriately preserved. They are rather tolerant to water hardness. 

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