Nucleosides and Nucleotides. 163. Synthesis of 3‘-β-Branched Uridine Derivatives via Intramolecular Reformatsky-Type Reaction Promoted by Samarium Diiodide<sup>1</sup>
作者:Satoshi Ichikawa、Satoshi Shuto、Noriaki Minakawa、Akira Matsuda
DOI:10.1021/jo961665f
日期:1997.3.1
A novel efficient method for the synthesis of 3'-beta-branched uridines starting from uridine was developed, in which a SmI2-promoted intramolecular Reformatsky-type reaction was effectively used. 5'-O-(Bromoacetyl)-3'-ketouridine derivatives 12, 26, and 27 were synthesized from uridine and were subjected to an intramolecular Reformatsky-type reaction. When 12, 26, and 27 were treated with 2.0 equiv of SmI2 in THF at -78 degrees C, intramolecular carbon-carbon bond formation at the 3'-beta-position proceeded smoothly to give the corresponding 3',5'-lactones 14, 28, and 29 in high yields, respectively. Treatment of 28 with NH3/MeOH gave the 3'-beta-branched uridine derivative 32 quantitatively, which was then deprotected to give 3'-C-(carbamoylmethyl)uridine (33).