A convenient synthesis of N-acetyllactosamine derivatives from lactal.
In a thermal inverse-type hetero-Diels-Alder reaction of O-silyl-protected lactal 1 and bis(2,2,2-trichloroethyl) azodicarboxylate (2), the dihydrooxadiazine derivative 3 was obtained in a very high yield; transesterification with benzyl alcohol furnished the corresponding derivative 4. Treatment of 3 with methanol in the presence of BF3.OEt2 afforded the methyl lactoside derivative 5 which, after transesterification with benzyl alcohol, then hydrogenolytic debenzylation and concomitant NN-cleavage with Raney nickel, and N-acetylation, furnished methyl O-(2,4,6-tri-O-tert-butyldimethylsilyl-beta-D-galactopyranosyl)-(1-->4)- 2-acetamido-3,6-di-O-tert-butyldimethylsilyl-2-deoxy-beta-D-glucopyra nos ide (7) in high yield. Desilylation of 4, then O-acetylation, methyl glycoside formation with methanol-BF3.OEt2, hydrogenolytic debenzylation, and NN-cleavage with Raney nickel, and N-acylation afforded methyl O-(2,3,4,6-tetra-O-acetyl-beta-D-galactopyranosyl)-(1-->4)-2-acetamido-3 ,6-di-O-acetyl-2-deoxy-beta-D-glucopyranoside (10).
Toepfer
A
A
Fakultät Chemie, Universität Konstanz, Germany.
Schmidt
R R
RR
D000606:Amino Sugars / Q000138:chemical synthesis* / Q000737:chemistry; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D007202:Indicators and Reagents; D007785:Lactose / Q000031:analogs & derivatives*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009904:Optical Rotation
D000606:Amino Sugars; D007202:Indicators and Reagents; C000458:N-acetyllactosamine; D007785:Lactose