Synthesis of 1,5,6,7-tetrahydroindol-4-ones from amino-sugars and cyclohexane-1,3-diones

Abstract

Reactions of 2-amino-2-deoxy-D-glucose with cyclohexane-1,3-diones produced 2-deoxy-2-(3-oxocyclohex-1-enylamino)-D-glucoses (1), which were cyclized to give 1,5,6,7-tetrahydro-2-(D-arabino-1,2,3,4-tetrahydroxybutyl)indol-4-ones (2). Other products of the cyclization reactions were the 1,5,6,7-tetrahydroindol-4-ones (5), the 2-(β-D-erythrofuranosyl)-1,5,6,7-tetrahydroindol-4-ones (6), and D-erythrose. Similar reactions with 1-amino-1-deoxy-D-fructose yielded the enamines (3), which were further transformed into 1,5,6,7-tetrahydro-3-(D-arabino-1,2,3,4-tetrahydroxybutyl)indol-4-ones (4). A series of formyl-1,5,6,7-tetrahydroindol-4-ones [(11) and (12)] were obtained by oxidation of compounds (2) and (4) with periodate.