Chemoenzymatic Synthesis of Novel 3‘- and 5‘-Carbazoyl Nucleoside Derivatives. Regioselective Preparation of 3‘- and 5‘-Alkylidencarbazoyl Nucleosides
摘要:
A chemoenzymatic procedure is described for the synthesis of 3'- and 5'-carbazoyl nucleoside derivatives 12a,b, 13a,b, 14b,c, and 30b, and these are prepared for the first time. This process involves the regioselective enzymatic alkoxycarbonylation of nucleosides and the subsequent transformation with hydrazine into novel carbazoyl nucleoside derivatives. Taking into account previously reported data (relative to nucleoside, hydrazone, carbazate, and aryloxyphenoxypropionate derivatives), 3'-alkylidencarbazoyl 2'-deoxynucleosides 15a,b-18a,b, 5'-alkylidencarbazoyl 2'-deoxynucleosides 19a,b-22a,b, 5'-alkylidencarbazoyl ribonucleosides of uridine 23c-26c, and 5'-alkylidencarbazoyl-2',3'-isopropylideneadenosine 31b-34b emerge as interesting targets since they combine structural features found in both therapeutic nucleoside derivatives and fungicide/herbicide nucleoside analogues.
Lipase-mediated alkoxycarbonylation of nucleosides with oxime carbonates.
摘要:
5'-O-carbonates of ribonucleosides and 2'-deoxyribonucleosides could be obtained by enzymatic alkoxycarbonylation with SP 435 lipase (from Candida antarctica) and oxime carbonates, which are easily prepared from chloroformates. Ribonucleosides gave as result two kind of 5'-O-carbonates depending on whether alkoxy or acetone oxime moiety acted as the leaving group. In the case of 2-deoxynucleosides, the leaving group was always the acetonoxime moiety, giving rise to regioselective formation of the corresponding 5'-O-alkyl carbonates, together with small amounts of 3'-O-regiosiomer and diacylated compounds.
The two step synthesis of 5'-O- and 3'-O-(N-alkylcarbamoyl)-nucleosides is described. The key step is the enzymatic synthesis of 5'-O- or 3'-O-alkoxycarbonylnucleoside in a regioselective way. In a second aminolysis step these carbonates yield the corresponding urethanes. This methodology allows to assemble aminoalcohols and L-amino acids to 2'-deoxynucleosides.