Synthèse et réactivité de nitro indazoles

Abstract

La synthèse et les propriétés spectroscopiques en rmn de 44 dérivés nitrés de l'indazole dont 23 sont décrits pour la première fois, ont été étudiées. En fonction des rendements, on indique la meilleure voie d'accés aux dérivés halogénés méthyle's (halogénation avant ou après méthylation du nitro indazole). La réactivité' relative des différents sites du cycle vis à vis de l'agent électrophile est discutée.

Synthesis, reactivity, and NMR spectroscopy of 4,6‐ and 6,7‐difluoro‐3‐methyl‐1H‐indazoles

“…The nitration of 1H-indazole itself 9 in strongly acidic conditions affords 5-nitro-1H-indazole 10 as the main product together with 5,7-dinitro-1H-indazole 11 in minor proportion [2,[17][18][19][20]. Further nitration of 10 leads to 11 [21].…”

“…We have been interested in 1H-indazoles for many years [1][2][3][4], some of them being potent inhibitors of the nitric oxide synthase (NOS) family of isozymes [5][6][7][8]. Amongst indazoles, 3-bromo-7-nitro-1H-indazole 1 (NIBr) is one of those that show highest affinity for type I NOS [9].…”

Crystal and molecular structure of three biologically active nitroindazoles

“…Bromination of 6 and 7 affords 1 and 2 [11,12]. The same compounds are obtained by methylation of 5 resulting in a 70/30 ratio of 1/2 [12]. With slightly different conditions, only 1 was obtained [14,15].…”

“…Bromination in acetic acid to afford 5 was reported by Auwers and Demuth in 1927 [10]. Treatment of 4 with methyl sulfate in basic conditions yields both N-methyl isomers 6 and 7 that can be easily separated [11][12][13]. Bromination of 6 and 7 affords 1 and 2 [11,12].…”

“…Treatment of 4 with methyl sulfate in basic conditions yields both N-methyl isomers 6 and 7 that can be easily separated [11][12][13]. Bromination of 6 and 7 affords 1 and 2 [11,12]. The same compounds are obtained by methylation of 5 resulting in a 70/30 ratio of 1/2 [12].…”