Enzymatic alkoxycarbonylation

This enzymatic alkoxycarbonylation is of great utUity in activating hydroxyl groups... 

An efficient and high-yielding enzymatic protocol for regioselective alkoxycarbonylation of the diol precursor of lo ,25-dihydroxyvitamin D3 has been accomplished. The procedure provided a convenient synthesis of the A-ring vinyl carbonate derivative, which is a useful synthon of vitamin D3 analogues for pharmaceutical research. ... 

In recent years biotransformations have also shown their potential when applied to nucleoside chemistry [7]. This chapter will give several examples that cover the different possibiUties using biocatalysts, especially lipases, in order to synthesize new nucleoside analogs. The chapter will demonstrate some applications of enzymatic acylations and alkoxycarbonylations for the synthesis of new analogs. The utQity of these biocatalytic reactions for selective transformations in nucleosides is noteworthy. In addition, some of these biocatalytic processes can be used not only for protection or activation of hydroxyl groups, but also for enzymatic resolution of racemic mixtures of nucleosides. Moreover, some possibilities with other biocatalysts that can modify bases, such as deaminases [8] or enzymes that catalyze the synthesis of new nucleoside analogs via transglycosylation [9] are also discussed. 

Quijada FJ, Rebolledo F, Gotor V. Enzymatic dynamic kinetic resolution of ( )-cw-JV-(alkoxycarbonyl)cyclopentane-1,2-diamines based on spontaneous racemization. Org. Lett. 2010 12 3602-3605. 

In method C, dienynes 193 are semihydrogenated to a previtamin structure that undergoes rearrangement to the corresponding vitamin D analog. The chemical synthesis developed in the Okamura laboratory for 194 (X = Y = H), starting with (5)-cavone, is probably the most efficient approach in this area [45], but the regioselective enzymatic acylations [46] and alkoxycarbonylations [47] of the four stereoisomers of 194 open the doors to a new family of synthon precursors to feed this route. 

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