Synthesis of 3-R-2-aryl-4,6-dinitroindoles and specific features of their reactions with anionic nucleophiles

Abstract

Reaction of different anionic S nucleophiles with 3 R 2 aryl 4,6 dinitroindoles led to a regiospecific nucleophilic substitution of the nitro group in position 4 with 6 NO 2 group remaining intact. The representatives of some peri annulated polycyclic systems were synthe sized on the basis of the substitution products.

Synthetic Utilization of Polynitroaromatic Compounds. 6. Remarkable Regioselectivity in Nucleophilic Displacement of Aromatic Nitro Groups with Amines

“…As mentioned above, dinitro-substituted benzoannulated heterocyclic systems (both five- and seven-membered) undergo selective nucleophilic displacement of the nitro group ( peri -group for five-membered heterocycles but para -group for the seven-membered one) with the various nucleophiles studied. − Thus, the incomplete selectivity of the nucleophilic substitution observed in the case of quinazolones and very strong dependence of the product ratio upon relatively minor changes of the structure of nucleophiles (i.e., AlkS - /ArS - and ArS - /ArO - ) 3b,20 are quite unusual. However, this is not at all unexpected; it is only natural to suppose that quinazolines, as six-membered benzoannulated heterocycles, should display a selectivity pattern somewhere between those of five- and seven-membered heterocycles.…”

“…It is known that dinitro-substituted benzoannulated five-membered heterocyclic systems  phthalimides, benzo[ b ]furans, indoles, 2a,b benzo[ b ]thiophenes, benz[ d ]isoxazoles, indazoles, benz[ d ]isothiazoles  undergo selective nucleophilic displacement of a nitro group adjacent to a ring fusion point ( peri -nitro group) with O-, N-, and S-nucleophiles. On the other hand, we recently demonstrated that with 1,3-dinitrodibenz[ b , f ][1,4]oxazepine-11(10 H )-one just the opposite occurs; the nonadjacent nitro group ( para -nitro group) is displaced with O- and S-nucleophiles (Scheme ).…”

Synthesis and Functionalization of 5,7‐Dinitroquinoline and Its N‐Oxide

“…Among functionalization methods of π‐deficient aromatic (benzo)heterocycles, nucleophilic substitution reactions play an important role as one of the most efficient tools to introduce various substituents into an aromatic core. Earlier, we reported the regiospecific nucleophilic substitution of 4‐NO 2 to various 4,6‐dinitrobenzoannulated five‐membered heterocycles, including benzo[ d ]isoxazoles, 1 H‐ indazoles, and indoles . In most cases, the nitro group in the 6‐position remained intact, both by using an excess amount of the nucleophile and under more drastic reaction conditions.…”

Functionalization of 4,6-dinitro-2-phenylindole at position 7

“…Previously, 3 we functionalized 2 aryl 4,6 dinitroin doles at position 3 and obtained various 4 substituted 3 R 6 nitroindoles via regiospecific nucleophilic substi tution of the 4 NO 2 group. Further transformations gave polycyclic peri annulated systems.…”