Synthesis Of Galactosamine Hydrochloride And Its Derivatives From D-tagatose

Aminogalactose is an important amino sugar compound that is widely present in living organisms.It plays an important role in the fields of anti-infection,cancer research,and treatment of liver diseases,so it is important to study its synthesis.This paper aims to develop a novel synthesis method of aminogalactose.which is rearranged by Heyns using D-tagatose as raw material to obtain N-benzyl-D-galactosamine,N-benzyl-D-galactosamine Hydrodebenzylation under the action of hydrochloric acid acidification and Pd/C catalyst gives D-galactosamine hydrochloride,and D-galactosamine hydrochloride is synthesized by a variety of acylation reactions to synthesize a series of aminogalactose derivatives.The reaction product was characterized by methods such as nuclear magnetic resonance and mass spectrometry.In the second chapter,we introduce the two-step synthesis of N-benzyl-D-galactosamine.The experiment explored the molar ratio of reactants,solvent selection,catalyst selection,reaction temperature,reaction time and other factors to obtain better reaction conditions,avoiding the problems of insufficient one-step reaction and high temperature.The molar ratio of D-tagatose to benzylamine is 1:2,methanol is used as solvent,and glacial acetic acid is used as isomerization catalyst.The reaction is carried out at 40? for 12 h,and the yield of N-benzyl-D-galactosamine is 75.3%.In the third chapter,we introduce the method of synthesizing D-galactosamine hydrochloride.In the study,N-benzyl-D-galactosamine was used as a raw material,and Pd/C was used as a catalyst to remove the benzyl group in the molecule under hydrochloric acid acidification and hydrogen atmosphere to obtain D-galactosamine hydrochloride.At a reaction temperature of 25?,the reaction time should be 24 h,The volume ratio of dioxane to water in the solvent is 1:1.,the pH is between 1 and 2,and the hydrogen pressure is 1.0 MPa.Under the above preferred reaction conditions,the yield of D-galactosamine hydrochloride calculated as D-tagatose was 55.4%.In the fourth chapter,we introduce the synthesis of a series of derivatives by D-galactosamine hydrochloride acylation.In the study,D-galactosamine hydrochloride was used as raw material,and different amino protecting agents were selected for nitrogen acylation,and then the hydroxyl group in the sugar molecule was protected with acetic anhydride to obtain a series of acylation reaction products.Focus on the use of diantipyrylmethane as a nitrogen protectant to obtain 1,3,4,6-tetra-O-acetyl-N-(1,3-dimethyl-2,4,6(1H,3H,The synthesis process of 5H)-trioxopyrimidine-5-ylidenemethyl-?-D-galactosamine was optimized,and the effects of catalyst type,type of acid binding agent,solvent type,reaction temperature and reaction time were investigated.Better reaction conditions are obtained.The 4-methylaminopyridine was used as a catalyst,triethylamine was used as an acid binding agent,methanol was used as a solvent,and the reaction was carried out at room temperature for 2 h,and the target product yield was 35.6%.