CONVERSION OF D-FRUCTOSE INTO 4-AMINO, 4-AMINO-4-C-METHYL AND 3,4,5-TRIAMINO-DERIVATIVES OF L-SORBOSE

Article abstract of DOI:10.1016/0008-6215(87)80141-6

The 1,5-dialdehydes generated via periodate cleavage of benzyl β-D-fructopyranoside (1) and 1,2-O-isopropylidene-D-fructopyranose (10) undergo cyclization with nitromethane with high stereoselectivity, yielding 4-deoxy-4-nitrohexulopyranoses of the α-L-sorbo (2, 11) and α-L-tagato- (4) configurations only, in 3:1 and 2:1 ratios, respectively.Nitroethane cyclization affords four methyl-branched 4-nitro-hexuloses with a 12:6:2:1 stereoselectivity, of which the major three have been isolated and characterized to be the α-L-sorbo (18), β-D-psico (20), and α-L-tagato (22) isomers.Hydrogenation of the nitro function smoothly generated, in high yields, the respective 4-amino-4-deoxyhexulopyranoses of the α-L-sorbo (14, 23), α-L-tagato (9), and β-L-psico (24) configurations.Subjection of the nitroacetates 2 and 11 to amination with methanolic ammonia - a double elimination-addition sequence - and, subsequently, to acetylation, furnished the 3,5-diacetamido-4-nitro-α-L-sorbopyranoses 7 and 15 in 53 and 64percent yields, respectively which were readily converted by hydrogenation into the respective 3,4,5-triamino-3,4,5-trideoxy-α-L-sorboses 6 and 16, representing the first triaminosugars of this type.Structural and configurational assignments were based on conclusive ¹H-n.m.r data, on rotational comparisons, and on stereochemical considerations, and were sustained by X-ray-crystallographic analyses of benzyl 4-deoxy-4-nitro-α-L-tagatopyranoside (5) and its methyl-branched analog 22.