A convenient synthesis of N-acetyllactosamine derivatives from lactal

✍ Scribed by Alexander Toepfer; Richard R. Schmidt

• Book ID: 102992882
• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 447 KB
• Volume: 247
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(93)84249-6

✦ Synopsis

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).