Tetradeoxy sugars, synthesis

Opening of the epoxide 101 with dimethylamine leads to two regioiso-meric dimethylamino alcohols, 104 and 105, in a ratio of 4 1. Catalytic hydrogenation of 104, lactonization by means of acetic anhydride, and DIBAH reduction of the lactone 106 completed a synthesis of racemic form of another antibiotic sugar, forosamine (107, 2,3,4,6-tetradeoxy-4-dimethylamino-DL-er-yf/iro-hexopyranose). When the starting epoxide 101 was resolved by means of its (-I- )-phenylethylammonium salt into enantiomers, the same reaction sequence... 

Purpurosamine B (382), a seven-carbon atom sugar component of the antibiotic gentamicin C2, was synthesized from 6-acetyl-5,6-dihydio-2-methoxy-2H-pyran (333, R = Me). Oximation of the keto group, reduction of the oxime to the corresponding amine, and N-acetylation gave two stereoisomeric N-acet-amides. For further synthesis the erythro stereoisomer (380) was taken. Further steps involved the epoxldation of the double bond, isolation of the manno epoxide, and its reduction to methyl 6-acetamido-3,4,6,7-tetradeoxy-a-DL-araI)i>io-heptopyranoside (381). Oxidation of the 2-OH group, oximation of the ketone, and reduction of the oxime followed by acetylation gave methyl N,N -diacetyl-a-DL-purpurosaminide B, which was hydrolyzed to N,N -diacetyl-DL-purpuro-samine B (383). 

Ring-opening of oxirans has been used in the synthesis of a number of amino-sugars, including a new synthesis of o-forosamine (4-dimethylamino-2,3,4,6-tetradeoxy-D-eryt/jro-hexose) (101) from sorbic acid (Scheme 24) the initial... 

A 2-acetamido-4-amino-2,4-dideoxy-P-D-glucopyranosyl residue was synthesized and incorporated as the terminal residue of a trisaccharide glycoside, in connection with studies of the acceptor requirements of N-acetylglucosaminyl transferase A 2-acetaniido-4-aniino-2,3,4,6-tetradeoxy-a-D-jiy/t>-hexopyranosyl residue was incorporated into a trisacchaiide-ribitol-phosphate, the repeat unit of a Streptococcus pneumoniae polysaccharide. The synthesis of diamino-sugar 58 is covered in Section 2.8. 

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