Synthesis of 3,7-Anhydro-<scp>d</scp>-<i>g</i><i>lycero</i>-<scp>d</scp>-<i>i</i><i>do</i>-octitol 1,5,6-Trisphosphate as an IP<sub>3</sub> Receptor Ligand Using a Radical Cyclization Reaction with a Vinylsilyl Tether as the Key Step. Conformational Restriction Strategy Using Steric Repulsion between Adjacent Bulky Protecting Groups on a Pyranose Ring
作者:Satoshi Shuto、Yumi Yahiro、Satoshi Ichikawa、Akira Matsuda
DOI:10.1021/jo0002339
日期:2000.9.1
3,7-Anhydro-D-glycero-D-ido-octitol 1,5,6-trisphosphate (5) was designed as a novel IP3-receptor ligand having a C-glycosidic structure and was synthesized via a radical cyclization reaction with a temporary connecting vinylsilyl tether as the key step. The phenyl 2-O-dimethylvinylsilyl-3,4,6-tri-O-benzyl-1-seleno-beta-D-glucopyranoside (7), in the usual C-4(1)-conformation, was successively treated with Bu3SnH/AIBN and under Tamao oxidation conditions to give a mixture of five C-glycosidic products, On the other hand, similar successive treatment of the corresponding 3,4-di-O-TBS-protected substrates 13 and 24, which were in an unusual C-1(4)-conformaion due to the steric repulsion between the bulky silyl protecting groups, gave the desired 1 alpha-C-glycosides 18 and 25, respectively, as the major products. Thus, the course of the radical cyclization was effectively controlled by a change in the conformation of the pyranose ring into a C-1(4)-form due to steric repulsion between the adjacent bulky TBS-protecting groups at the 3- and 4-hydroxyl groups. From 25, the target 5 was synthesized via phosphorylation of the hydroxyls by the phosphoramidite method. The C-glycoside trisphosphate 5 has significant binding affinity for IP3 receptor of calf cerebella.