T. P. Surikova

Nitration of 5-formyl-substituted 2-cyclopropylfurans and 2-methylfurans and the corresponding thiophenes

In the nitration of 5-formyl-substituted 2-cyclopropylfurans and the corresponding thiophenes, in addition to the formation of the corresponding 3-nitro derivative the replacement of the formyl group by a nitro group takes place. For a thiophene derivative the latter direction of the reaction is observed to a substantially smaller degree. Under nitration conditions, 5-formylsylvane is converted only into 5-nitrosylvane, while the corresponding formylmethylthiophene is nitrated exclusively in position 3. The difference observed in the behavior on nitration of the furans and thiophenes studied is explained by the different degrees of participation of the heteroatom in the delocalization of the charges in the heterocyclic ipso-ions formed as intermediates.

Ipso attack in the nitration of 5-bromo- and 5-methyl-2-cyclopropylthiophenes

It was established that 5-bromo-2-cyclopropylthiophene and 5-methyl-2-cyclo-propylthiophene undergo transformations during nitration with nitric acid in acetic anhydride that are a consequence of ipso attack of the nitryl cation in the 2 or 5 positions of the thiophene rings of the starting compounds.

Synthesis and biological activities of substituted 2- and 3-chloropropylthiophenes

Beginning in 1970 we have systematically studied the potential reactivities and biological properties of several thiophene derivatives. In these studies special attention was paid to development of synthetic methods for various functionally substituted cyclopropylthiophenes. It was proposed that the strength of the electronic bonds in the triangular ring would confer special biological properties on its derivatives. Particular attention was paid to obtaining cyclopropylthiophenes substituted with electron-accepting groups in the heterocyclic ring, which according to the literature [2] increases the antibacterial activity of several medicinal compounds in comparison with unsubstituted analogs or analogs substituted with electron-donating groups.

Synthesis and nitration of some 4-cyclopropyl- and 4-(p-cyclopropylphenyl)-2-aminothiophenes

A number of cyclopropyl-substituted crotononitriles have been synthesized by a Knoevenagel condensation. Reaction of these compounds with sulfur in the presence of a base gives substituted 4-cyclopropyl- and 4-cyclopropylphenyl-2-aminothiophenes, while nitration of some acetylaminothiophenes with acetyl nitrate in acetic anhydride at low temperature gives the corresponding nitro derivatives.

Behavior of 2-nitroso-4-nitropropiophenone under conditions of cyclization to haloanthranils

The cyclization of 2-nitroso-4-nitropropiophenone under the influence of hydrogen chloride proceeds in a more complex manner than in the cases previously described for other 4-substituted-2-nitrosopropiophenones: three, rather than two, haloanthranils are formed, and their formation is accompanied simultaneously by a number of redox transformations. This fact is explained by a decrease in the ability of the carbonyl group in the investigated ketone to undergo protonation.

Reaction of 2-cyclopropylthiophenes with mercuric acetate

The reaction of 2-cyclopropylthiophene with mercuric acetate in methanol takes place only in the thiophene ring. 5-Methyl-2-cyclopropylthiophene undergoes mercuration in both the heterocyclic ring and in the three-carbon ring (the Levina reaction).

New information regarding the transformations of furans under nitration conditions. Direct oxidative cleavage of 2-cyclopropyl- and 5-methyl-2-cyclopropylfurans by means of a nitrating agent

The principal pathway of the reaction of 2-cyclopropylfurans with acetyl nitrate in acetic anhydride or with nitrogen tetroxide in methylene chloride is cleavage of the furan ring with the formation of unsaturated 1,4-dicarbonyl compounds. Nitro-furylcyclopropanes are formed in low yields via an independent pathway under these conditions. The possible pathways of nonhydrolytic cleavage of the furan ring under anhydrous nitration conditions are discussed.