127(P78) カルシウムイオン結合性スフィンガジエニン型糖脂質の合成研究(ポスター発表の部)
スポンサーリンク
概要
- 論文の詳細を見る
Glucocerebrosides (1a, 1b) having 4,8-sphingadienine in the hydro-phobic moiety have attracted current interests because of their calcium-ionophoretic activities and biological activities. Here we report a synthetic approach to 1a and 1b using vinyl-epoxide (8), prepared from D-glucosamine, for the synthesis of the sphingadienine moiety. Thus, N-benzoyl-D-glucosamine (2) was converted into the vinyl-epoxide derivative (8) in ca. 40% over-all yield. Treatment of 8 with a higher order cyanocuprate (12) derived from 2-dodecenyllithium afforded 4,8-sphingadienine derivatives as a 1:1 mixture of the (4E,8E)-isomer (13a) and the (4E,8Z)-isomer (13b), both of which resulted from α, γ'-regio-selective cross-coupling. Alternatively, 8 was treated with cyanomethyl-lithium in the presence of CuI to give the nitrile (14) in high yield. Subsequent DIBAL reduction and Wittig olefination gave the (4E,8Z)-isomer (13b) predominantly. (RS)-2-Hydroxypalmitic acid was resolved via condensation with (4R,5S)-4-methyl-5-phenyl-1,3-oxazolidine-2-thione (16) and chromatographic separation of the diastereomeric products. Coupling of 1-O-benzoyl-4,8-sphingadienine (18) and (2R)-hydroxypalmitic acid in the presence of dicyclohexylcarbodiimide and N-hydroxysuccinimide gave the ceramide (19), which was converted to a glucosyl-acceptor (20). Glycosylation of 20 as well as efficient separation of (8E)- and (8Z)-isomers is now in progress.
- 天然有機化合物討論会の論文
- 1996-09-02