208524-53-2Relevant academic research and scientific papers
Synthesis of methyl 5a′-carba-β-lactoside and N-acetyl-5a′-carba-β-lactosaminides, and related 5a′-carbadisaccharides
Ogawa, Seiichiro,Hirai, Keisuke,Odagiri, Takashi,Matsunaga, Naoki,Yamazaki, Tetsuya,Nakajima, Akihiro
, p. 1099 - 1109 (2007/10/03)
Construction of the ether-linked methyl 5a′-carba-β-lactoside (3) and N-acetyl-5a′-carba-β-lactosaminide (4) were carried out starting from the coupling products 15 and 16, readily obtained by coupling between 1,2-anhydro-4,6-O-benzylidene-5a-carba-D-mannopyranose (7) and the oxide anions generated from methyl 2,3,6-tri-O-benzyl-β-D-glucopyranoside (8) and methyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside (10), respectively. Their 5a-carba-α-D-mannopyranose moieties were transformed into those of 5a-carba-β-D-galactopyranose by a sequence of reaction: Oxidation of the 2′-OH group, epimerization of the C-1′ with DBU, selective reduction of the carbonyl group, and epimerization of the C-4′ via oxidation and then reduction of 4′-OH or SN2 reaction of the 4′-mesylate with an acetate anion. Reaction of 1,2-anhydro-6-O-benzyl-3,4-O-isopropylidene-5a-carba-α-D-galactopyranose (6), initially expected as the potential donor, with these oxide anions did not give any ether-linked products, rather resulting in elimination reaction of 7. However, coupling of the epoxide 6 with methyl 2-acetamido-4-amino-2,4-dideoxy-β-D-glucopyranosides (19) easily gave rise to imino-linked 5a′-carbadisaccharide derivative 38, which, after deprotection, gave the imino-linked congener 5. On the other hand, two biologically interesting carbadisaccharides including methyl N,N′-diacetyl-5a′-carbachitobioside (45) were obtained from the versatile intermediate 24.
