comparative study on the substraterecognition was conducted successfully in Novozym 435-mediated acylation of various 2′- or 5-substituted nucleosides with acyl donors carrying different aliphatic chain lengths (C6, C10, and C14). The unexpected results revealed that the physicochemical property of the substituents (such as the size, hydrophobicity, and substitutional position) in nucleosides profoundly influenced
A useful and versatile procedure for the acylation of nucleosides through an enzymic reaction
作者:Francisco Moris、Vicente Gotor
DOI:10.1021/jo00055a018
日期:1993.1
Lipase-mediated acylation of nucleosides with oxime esters in organic solvents has been achieved. Candida antarctica lipases (SP435 and SP435A) showed high regioselectivity toward the primary hydroxyl group of both deoxy- and ribonucleosides, whereas other lipases exhibited poor results for this goal. 2'-Deoxynucleosides, such as thymidine and 2'-deoxyadenosine, were acylated with oxime esters carrying saturated, unsaturated, aromatic, and functionalized chains, giving 5'-O-acylated compounds together with small quantities of the 3'-O-acylated regioisomer. Uridine, adenosine, and inosine, as representative ribonucleosides, were acylated exclusively at the 5'-OH by using the same methodology. Nucleosides bearing a cytosine ring were found to be unreactive with oxime esters under the same conditions. 2'-Deoxycytidine was acylated with acid anhydrides and C. antarctica lipase to give N,5'-O-diacylated compounds, whereas cytidine gave mixtures, reason for which it had to be previously chemically N-acylated and then subjected to the oxime esters and lipase, giving the same results as ribonucleosides.