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Abstract
Condensation of 2,3,4,5-tetra-O-acetyl-galactaroyl dichloride (1) with two equivalents of the α-amino esters 2a–c gave the corresponding 2,3,4,5-tetra-O-acetyl-galactaric acid diamides 3a–c. Heterocyclization of 3a–c by heating with hydrazine hydrate took place with concomitant de-O-acetylation of the polyacetoxyalkyl chain to give 1,4-bis[1-amino-5-oxo-4-substituted(imidazolin-2-yl)] galacto-tetritols (5a–c) and not the theoretically possible 1,2,4-triazinones 4 as indicated by spectral data. Compounds 5a–c readily reacted with p-nitrobenzaldehyde to give the corresponding p-nitrobenzylideneamino derivatives 6a-c. Acetylation of 5a–c afforded the 2,3,4,5-tetra-O-acetyl-1,4-bis[1-acetamido-5-oxo-4-substituted(imidazolin-2-yl)]galacto-tetritols (7a,b,d). De-O-acetylation of 7a,b,d gave 1,4-bis[1-acetamido-5-oxo-4-substituted (imidazolin-2-yl)]galacto-tetritols (8a–c).