Synthesis of amino-substituted hexo- and heptopyranoses from D-galactose
Benedikt Streicher1, Bernhard Wünsch
1Institut für Pharmazeutische und Medizinische Chemie der Westfälischen Wilhelms-Universität Münster, Hittorfstrasse 58-62, D-48149 Münster, Germany.
Abstract:
After condensation of D-galactose with two equivalents of acetone, the last free hydroxy group was transformed into an acylated amino group by Swern oxidation, oxime formation, LiAlH4 reduction and acylation. The intermediate aldehyde was homologated with the Wittig reagent, (methoxymethyl)triphenylphosphonium chloride, to afford, after careful hydrolysis, a homologous heptodialdo-1,5-pyranose. Condensation of the aldehyde with hydroxylamine and subsequent LiAlH4 reduction provided a bis-O,O-isopropylidene-protected 7-amino-6,7-dideoxygalactoheptopyranose, which was acylated with various carboxylic acid derivatives. The isopropylidene protective groups were cleaved by careful hydrolysis or alcoholysis to yield 6-acylamino-6-deoxy-galactopyranoses and 7-acylamino-6,7-dideoxy-galactohepto-pyranoses.
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