5-Diazo-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles in [3+2] cycloaddition reactions

Abstract

Keywords: dimethyl acetylenedicarboxylate, 1,3-and 2,3-substituted 5-diazo-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles, maleic anhydride, [3+2] cycloaddition.In the last ten years the range of indazole derivatives with valuable biological activity has increased substantially. Among them agonists of estrogen receptors [1] and dopamine D3 receptors [2], HIV protease inhibitors [3], and new anti-inflammatory substances [4] have been discovered. In this connection in a continuation of researches on the synthesis of 4,5-bifunctional 6,7-dihydro-and 4,5,6,7-tetrahydroindazoles [5-10] we realized [3+2] cycloaddition reactions between 5-diazo-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles 1a-d and maleic anhydride.The diazoindazoles 1a,b,d were obtained by the decomposition of the corresponding tosylhydrazones 2a,b,d in a water-ethanol solution of sodium hydroxide according to the procedure in [11,12] that we used earlier for the preparation of the diazoindazoles 1c and 3.

Diazocarbonyl and Related Compounds in the Synthesis of Azoles

“…In 2007, Strakova and co-workers reported the synthesis of spiro-3 H -pyrazoles adducts 252 and 254 by [3+2] cycloaddition of DMAD to diazo compounds 251 and 253 , respectively ( Scheme 62 ) [ 127 ]. The reaction proceeded smoothly at room temperature; however, the reaction took four days to go to completion.…”

Reactions of 1-aryl- and 2,3-diaryl- 5-diazo-6,6-dimethyl-4-oxo-4,5,6,7-tetra- hydroindazoles with N-ethyl- and N-phenyl-substituted maleimides

“…This led to the formation of the corresponding 3-spiropyrazoline and pyrazole derivatives of 4,5,6,7-tetrahydroindazole [25].…”