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Please login or sign up for a free trial to access the full content. Method 3: Transesterification with Enzymes

DOI: 10.1055/sos-SD-020-00774

Zhang, M.; Hanson, P. R.Science of Synthesis, (200720932.

Transesterification is one of the reactions for which enzymes are utilized most effectively and this technology has experienced explosive expansion since about 1990.[‌339‌] Most of the enzymes involved in this technology are lipases, an indication of the pivotal position of these enzymes. Takabe and co-workers reported a highly regioselective transformation of various acyclic α,ω-terpenediols to monoacetates, e.g. 254, by lipase-catalyzed transesterification (Scheme 88).[‌367‌] Short-chain citronellyl esters, e.g. 255, are synthesized by transesterification reactions catalyzed by a new microbial lipase from a Rhizopus sp. strain, isolated in a solvent-free system or with hexane in the reaction medium; yields are up to 60% after 48hours (Scheme 88).[‌368‌] These results suggest that the size of the aliphatic chain from the acyl donor is important for the conversion rate. There is a unique regioselectivity between primary alcohols too (Scheme 88).[‌369‌] The 4-hydroxy group of diol 256 undergoes exclusive transesterification by isopropyl acetate with the aid of Candida cylindracea lipase to give 4-hydroxybutyl acetate 257 (Scheme 88).

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