Total synthesis of a modified ganglioside, de-N-acetyl GM2.
Regio- and stereo-selective glycosylation of a sialyl donor 6 that carries a N-phthaloyl protecting group at C-5 with a lactosyl acceptor 7 armed with a pivaloyl group at O-2a was performed to give the expected glycotrioside 5. Subsequent glycosylation of 5 with 2-azido galactosyl donor 4 gave glycotetraosyl derivatives 18 and 19. After conversion of 18 into imidates 25 and 26, coupling with (2S,3R,4E)-3-O-benzoyl-2-N-tetracosanoylsphingenine (2) was executed to afford completely protected ganglioside analogues 27 and 28. Selective cleavage of the methyl ester and N,O-deprotection gave the target de-N-acetyl GM2 (1).
Fujita
S
S
Tokyo Research Institute, MECT Co., Saitama, Japan.
Numata
M
M
Sugimoto
M
M
Tomita
K
K
Ogawa
T
T
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D005678:G(M2) Ganglioside / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D006031:Glycosylation; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009904:Optical Rotation; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013237:Stereoisomerism
D007202:Indicators and Reagents; C091216:de-N-acetyl-GM2; D005678:G(M2) Ganglioside