1313374-91-2Relevant academic research and scientific papers
Studies on the stereoselective synthesis of a protected α-D-Gal-(1→2)-D-Glc fragment
Chen, Langqiu,Shi, Shen-De,Liu, Yong-Qing,Gao, Qing-Jiao,Yi, Xing,Liu, Kai-Ke,Liu, Hao
, p. 1250 - 1256 (2011/07/09)
A novel 1,2-cis stereoselective synthesis of protected α-D-Gal- (1→2)-D-Glc fragments was developed. Methyl 2-O-acetyl-3-O-allyl-4,6-O- benzylidene-α-D-galactopyranosyl-(1→2)-3-O-benzoyl-4, 6-O-benzylidene-α-D-glucopyranoside (13), methyl 2-O-acetyl-3-O-allyl-4,6- O-benzylidene-α-D-galactopyranosyl-(1→2)-3,4,6-tri-O-benzoyl-α- D-glucopyranoside (15), methyl 2-O-acetyl-3-O-allyl-4,6-O-benzylidene-α-D- galactopyranosyl-(1→2)-3-O-benzoyl-4,6-O-benzylidene-β-D- glucopyranoside (17), and methyl 2-O-acetyl-3-O-allyl-4,6-O-benzylidene-α- D-galactopyranosyl-(1→2)-3,4,6-tri-O-benzoyl-β-D-glucopyranoside (19) were favorably obtained by coupling a new donor, isopropyl 2-O-acetyl-3-O-allyl- 4,6-O-benzylidene-1-thio-β-D-galactopyranoside (2), with acceptors, methyl 3-O-benzoyl-4,6-O-benzylidene-α-D-glucopyranoside (4), methyl 3,4,6-tri-O-benzoyl-α-D-glucopyranoside (5), methyl 3-O-benzoyl-4,6-O- benzylidene-β-D-glucopyranoside (8), and methyl 3,4,6-tri-O-benzoyl-β- D-glucopyranoside (12), respectively. By virtue of the concerted 1,2-cis α-directing action induced by the 3-O-allyl and 4,6-O-benzylidene groups in donor 2 with a C-2 acetyl group capable of neighboring-group participation, the couplings were achieved with a high degree of α selectivity. In particular, higher α/β stereoselective galactosylation (5.0:1.0) was noted in the case of the coupling of donor 2 with acceptor 12 having a β-CH3 at C-1 and benzoyl groups at C-4 and C-6.
