Galactosylamine preparation

S)-fl-Amino acids.1 The Mannich reaction of the Schiff base 1, prepared from 2,3,4,6-tetra-O-pivaloyl-fl-D-galactosylamine, reacts with the silyl ketene acetal 2 in... 

Kunz and coworkers reported the application of an immobilized chiral galacto-sylamine in diastereoselective synthesis of piperidine and amino acid derivates [14]. Preparation of the galactosylamine auxiliary from 1,6-hexandiol and P-D-galactopyranosyl azide (1) required a six-step synthesis protocol. The precursor 2 was loaded onto a polymer bound silane. Reduction of the azide function gave the corresponding immobilized amine 3 (Scheme 12.2). 

Deoxy-D-well studied as the o-erythro isomer. It has been prepared in two ways from the decomposition of l,l -(carboxymethylamino)bis(l-deoxy-D-tagatose), ( di-D-tagatosegly-cine ), and from iV-butyl-D-galactosylamine. " These two methods and the isolation procedures are similar to the corresponding ones described for the erythro isomer. The 3-deoxy-n-i/ireo-hexosulose (42) was obtained as a colorless, amorphous powder, [ ]d + 10° — + 12.7° (in water), and was characterized as osazones. The (2,5-dichlorophenyl)osazone and the (2,4-dinitrophenyl)osazone are crystalline, the latter yielding a triacetate. " ... 

Chen et al. have described a convenient and efficient synthetic protocol for preparation of a-aminophosphinic acid derivatives (583) in high yields and high enantiostereoselectivity, utilizing SnCU as the promoter and O-pivaloylated D-galactosylamine in (582) moiety as a chiral auxiliary by means of a Mannich-type reaction (Scheme 143). 

With ammonium chloride as a catalyst, Frush and Isbell (3) obtained two D-galactosylamines, one as a complex with one mole of ammonia these apparently represent a- and iS-pyranoid isomers. Diglycosylamines may also form in this type of preparation, since two isomeric di-D-glucosylamines were prepared under very similar conditions (4). 

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