72 糖タンパク質高マンノース型糖鎖の合成研究(口頭発表の部)

概要

論文の詳細を見る
In order to establish an efficient route for the synthesis of a high-mannose type glycan chain, the target tetradecasaccharide (1) was divided into three blocks, (A), (B) and (C) by retrosynthetic consideration. Synthetic routes for these blocks were established as follows. Block (A) Trisaccharide (4), a synthetic equivalent of (A), was obtained by condensation of mannosyl donor (2) with chitobiosyl acceptor (3) in the presence of silver silicate. Block (B) and (D) In order to study model reactions, we designed a hexasaccharide (D) and three synthetic approaches were examined. i) A stepwise approach using monosaccharide donors (8), (10) and (12): The glycosyl donors (8) and (10) were reacted stercoselectively with glycosyl acceptors (7) and (9), respectively, in the presence of silver triflate to give only α-anomers. The condensation of nonreducing end donor (12) with (11) in the presence of mercuric cyanide proceeded only in low yield. ii) A block synthesis using a disaccharide donor (13): Mercuric cyanide promoted glycosylation of (13) with (9) gave an anomeric mixture of hexasaccharides (α:β ratio 2:1, at 6'-O) in 18%. iii) Block synthesis using pentasaccharide donors (15), (16), and (17): Condensation of peracetylated pentasaccharide donor (15) with (14) in the presence of silver triflate gave only orthoester (19). However, a 14% yield of hexasaccharide (20) was obtained by condensation of (16) with (14) in the presence of mercuric salts, although the product could not be purified from contaminated mercuric salts. Pentasaccharide donor (17) was also reacted with (14) in the presence of a mixture of mercuric salts and a 23% yield of hexasaccharide (21) was obtained. Block (C) A linear hexasaccharide (29), was synthesized using disaccharide synthons (22), (23), and (25). The reaction of (22) with (23) in the presence of silvertriflate in dichloroethane gave a 59% yield of (28) which was converted to peracetylated donor (24). A 56% yield of the desired hexasaccharide (29) was obtained by condensation of (24) with (25) in the presence of silver triflate in dichloroethane. Further experiments directed toward a total synthesis of (1) will be discussed.
天然有機化合物討論会の論文
1988-09-26

72 糖タンパク質高マンノース型糖鎖の合成研究(口頭発表の部)

スポンサーリンク

概要

著者

関連論文

スポンサーリンク