| Abstract
| - A novel efficient method for the synthesis of 3‘-β-brancheduridines starting from uridine wasdeveloped, in which a SmI2-promoted intramolecularReformatsky-type reaction was effectivelyused. 5‘-O-(Bromoacetyl)-3‘-ketouridine derivatives12, 26, and 27 were synthesized fromuridineand were subjected to an intramolecular Reformatsky-type reaction.When 12, 26, and 27weretreated with 2.0 equiv of SmI2 in THF at −78 °C,intramolecular carbon−carbon bond formation atthe 3‘-β-position proceeded smoothly to give the corresponding3‘,5‘-lactones 14, 28, and 29 inhighyields, respectively. Treatment of 28 withNH3/MeOH gave the 3‘-β-branched uridinederivative32 quantitatively, which was then deprotected to give3‘-C-(carbamoylmethyl)uridine(33).
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