Diazo Derivatives of Sugars. Synthesis of methyl 2-deoxy-2-Diazo-d-arabino-Hexonate, Its Behaviour on Photolysis and Thermolysis, and Conversion into a Pyrazole Derivative

Article abstract of DOI:10.1016/S0008-6215(00)85734-1

The action of nitrous acid on methyl 2-amino-2-deoxy-d-gluconate hydrochloride (5) and acetylation of the product gives methyl 3,4,5,6-tetra-O-acetyl-2deoxy-2-diazo-d-arabino-hexonate (6); 4,6-O-benzylidene analogs of the methyl (4) and ethyl (3) esters are similarly prepared. Photolysis of the diazo sugar 6 in isopropyl alcohol gives mainly methyl 3,4,5,6-tetra-O-acetyl-2-deoxy-d-arabino-hexonate (13) and a small proportion of methyl 4,5,6-tri-O-acetyl-2,3-dideoxy-trans,-d-erythro-hex2-enoate (14), whereas photolysis of 6 in methanol gave a cis,trans mixture of methyl 3,4,5,6-tetra-O-acetyl-2-deoxy-d-erythro-hex-2-enoate (10); the same mixture (10) of enol acetates was obtained by thermolysis of 6. The diazo sugar 6 underwent cycloaddition with phenylacetylene to give a crystalline (R or S)-3-(d-arabino-tetraacetoxybutyl)-3-methoxycarbonyl-5-phenyl-3H-pyrazole (9) in 85% yield.