| Summary: | 碩士 === 國立中興大學 === 化學系所 === 103 === The synthesis of the ganglioside Hp-s1 analogue by changing the stereochemistry at C-1 position of glucosyl moiety is presented. In order to explore the exact stereochemical role of C-1 position of glucosyl moiety, we synthesized ganglioside analogue having alpha-alpha/alpha-beta configuration from non-reducing to reducing end. The characteristic sequence of the glycolipid part was efficiently assembled by coupling of a highly active benzyl protected glucosyl donor and a phytosphingosine derived acceptor with good -stereoselectivity. The corresponding glycolipid acceptor was directly glycosidated with the acetyl-protected sialyl donor part to afford the disaccharide in high yield and stereoselectivity. After amidization formation and global deprotection, ganglioside Hp-s1 analogue (2b) was obtained.
Synthesis of phthaloyl protected sphingosine derivative was achieved from commercially available phytosphingosine. In order to increase reactivity of primary hydroxyl group for further glycosylation, the unfavourable hydrogen bonding between primary hydroxyl group with amino group was replaced by installing phthaloyl protected group at N-H position. The reaction sequence as follows: Phthaloyl protection at N-H, benzylidene insertion at C-1 and C-3, iodination at C-4, elimination of iodide and deportection provided the protected sphingosine derivative.
|
|---|
