Isolation and structure determination of a new inosine derivative of a marine natural product

Abstract

During the study on the biologically active compounds from Ligia Exotica, a new O$^\prime$-glycosyl inosine has been isolated as a new inosine nucleic acid derivative. It has been postulated that the new natural product is 3$^\prime$-O-glucosyl inosine derivative by $^1H$ NMR, $^{13}C$ NMR,FAB-MS, and UV spectra. In order to elucidate the structure, total synthesis has been examined. As a starting material, $^1N$-benzyl 5$^\prime$-O-acetyl inosine was used. It reacted with O-(2,3,4,6-tetra-O-benzyl-$\alpha$-glucosyl) trichloroacetimidate in the presence of $BF_3$ . $ET_2O$ in $CH_2Cl_2$ to give four different glucoside isomers, which were separated by preparative tlc (silica gel,solvent; $CH_2Cl_2$ : MeOH=30:1) after their deacetylation. Their debenzylation gave four different O$^\prime$-glucosyl inosine isomers. $^1H$-and $^{13}C$-nmr spectra of one of the four glucosides are identical with these from the natural product. I was concluded that new marine natural product is 3``-O-$\alpha$-glucosyl inosine by comparing the $^1H$,$^{13}C$ NMR chemical shifts of each four isomer with those of various spectral data which are already known.