Synthesis of a linear tetrasaccharide unit of a complex type of glycan chain of a glycoprotein

✍ Scribed by Tooru Kitajima; Mamoru Sugimoto; Tomoo Nukada; Tomoya Ogawa

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 290 KB
• Volume: 127
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(84)85120-4

✦ Synopsis

As part of a project on the synthesis of a complex type of glycan of a glycoprotein' such as 1, we report here a regiocontrolled synthesis of the linear glycan unit 2 together with its stereoisomer 3, which corresponds to the nonreducing end tetrasaccharide structure of 1. In close connection with this report, it is to be noted that an elegant synthesis of the trisaccharide cw-NeuSAc-(2+6)&Gal-(l-+GlcNAc was recently reported by Paulsen and Tietz3. 1 i 3 /3Man(l-.-4)PGlcNAc(l-4),?GIcNAc~l--wAsn 6 We designed the trihexosyl acceptor 8 as the key intermediate which should be glycosylated with the readily available donor4 10. The key intermediate diol 8 was prepared as follows. The trihexosyl derivative 4 (ref. 5) was converted, via 5 (RF 0.48 in 3 : 1 CHCls-MeOH), in 3 steps, into the isopropylidene derivatives 6 and 7, in 69 and 11% overall yields, respectively; (i) NaOMe-MeOH, (ii) MezC(OMe)2-TsOH in DMF for 1.5 h at 20°, and (iii) AczO-pyridine. Compound 6: [(Y]_D *** t23.5" (c 1.33);R~ 0.40in I:3 tohrene-EtOAc; &j (CD&):