C-Branched pyrrolidines from 2-C-acetylmethyl-glycosylazides. Reduction of imines formed by monosaccharide ring opening.
Reduction of the protected 2-C-acetylmethyl-beta-glucopyranosyl azide derivative 1 produced the corresponding beta-glucosylamine 3. Rather than forming a conformationally strained 1,2-trans-fused bicyclic imine, we propose that the beta-glycosylamine underwent anomerization to an acyclic imine (4) followed by an intramolecular ring closure by the 5-hydroxy group. The resultant 2-C-acetylmethyl-alpha-glucopyranosylamine 5, which possesses the 1,2-cis-configuration was immediately converted to a bicyclic imine (2) in excellent yield. Attempts to selectively reduce the C=N double bond of 2 using sodium borohydride and cyanoborohydride failed to produce bicyclic amine 6. Instead, compound 6 underwent another ring-opening elimination and further reduction to produce a C-branched pyrrolidine (8) in good yield. Catalytic hydrogenation of 1 and 2 also provided the C-branched pyrrolidine (10).
Shao
Huawu
H
Institute for Biological Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6.
Williams
Dean T
DT
Wu
Shih-Hsiung
SH
Zou
Wei
W
D001386:Azides / Q000737:chemistry*; D002236:Carbohydrate Conformation; D003500:Cyclization; D007097:Imines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D009005:Monosaccharides; D010084:Oxidation-Reduction; D011759:Pyrrolidines / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D001386:Azides; D007097:Imines; D009005:Monosaccharides; D011759:Pyrrolidines; C032519:pyrrolidine