E. V. Trofimova

Synthesis of o-nitrosoacylbenzenes from o-nitrobenzyl alcohols and their derivatives

Nitration of substituted benzyl alcohols, as well as ethers and esters derived therefrom, with nitric acid in acetic anhydride was studied. The corresponding o-nitrobenzyl alcohols and their derivatives formed as the primary products are capable of being converted into o-nitrosoacylbenzenes by the action of acids.

1,1-Dihalo-2-benzycyclopropanes in reaction with nitrous acid

Interaction of 1,1-dichoro and 1,1-dibromo-2-benzylcyclopropanes with nitrous acid generated in situ was studied. It was shown that both nitration of the aromatic ring and heterocyclization of 1,1-dihalo-2-benzylcyclopropanes take place. Heterocyclization is initiated by opening of the cyclopropane ring in the reaction with nitrosyl cation. The nature of halogen atom in the cyclopropane ring affects the regioselectivity of the reactions.

N-acylaminophenylcyclopropanes in reaction with nitrous acid generated in situ

The reaction of N-acylaminophenylcyclopropanes with HNO2 proceeds regioselectively with introduction of an N = O fragment into the three-membered ring and formation of the corresponding Δ2-isoxazolines. For ortho-substituted N-acylaminophenylcyclopropanes side processes were observed, caused by the intramolecular participation of the N-acyl group in conversions of the carbenium ions formed on opening the cyclopropane ring under the action of the nitrosating reagent, and by direct insertion of the modified ortho substituent into the three-membered ring.

Direct synthesis of ethers from aldehydes and ketones. One-pot reductive etherification of benzaldehydes, alkyl aryl ketones, and benzophenones

Benzyl alcohols formed by the reduction of benzaldehydes, alkyl aryl ketones, and benzophenones with sodium tetrahydridoborate in alcohols undergo in situ etherification with the solvent in the presence of a catalytic amount of HCl. Thus the process may be regarded as one-pot transformation of carbonyl compounds into the corresponding benzyl ethers. The yields of ethers depend on the substituent nature in the aromatic fragment of the initial carbonyl compound and on the alcohol used as reduction medium.

Hydrochloric acid as an efficient catalyst for intermolecular condensation of alcohols. A simple and highly efficient synthesis of unsymmetrical ethers from benzylic alcohols and alkanols

Benzylic alcohols and diarylmethanols with electron-donating substituents in the aromatic ring reacted with aliphatic alcohols in the presence of a catalytic amount of HCl to give the corresponding alkyl arylmethyl ethers. The reactivity of diarylmethanols in the intermolecular dehydration depended on the nature of substituents in the aromatic rings and structure of aliphatic alcohol.

Benzyl-4,5-dihydroisoxazoles from benzylcyclo-propanes: regioselective insertion of an n=o fragment into the three-membered carbocycle of benzylcyclopropanes by the action of nitrous acid

The action of equimolar amounts of nitrous acid formed in situ on benzylcyclopropanes with electron-donor and electron-withdrawing substituents in the aromatic part of the substrate lead, at certain temperatures, exclusively to the insertion of an N=O fragment into the three-membered carbocycle with subsequent formation of a heterocyclic isoxazoline (4,5-dihydroisoxazole) system.

o-Acylbenzonitriles: Synthesis and Heterocyclization under Acid Hydrolysis of the Cyano Group

Abstract2-Cyanobenzophenones were synthesized by reaction of 2-bromobenzophenones with copper(I) cyanide in DMF, and their transformations involving acid hydrolysis of the cyano group were studied. Reactions of o-benzoylbenzonitriles with trifluoroacetic acid in the presence or in the absence of sulfuric acid afforded 3-hydroxyphthalimidines in high yields. Under analogous conditions, benzonitriles having no acyl group in the ortho position were converted to the corresponding benzamides. 2-Cyanobenzophenones reacted with sulfuric acid in the absence of trifluoroacetic acid to give only substituted anthraquinones.

Synthesis of quinolin-2-ones from ortho-vinylcarbonylamino-substituted acylbenzenes by tandem Michael and Knoevenagel reactions

Consecutive Michael addition and Knoevenagel intramolecular condensation reactions provide 3-alkoxymethyl-, 3-aminomethyl-, and 3-benzylquinolin-2-ones from o-(vinylcarbonylamino)acyl-benzenes. The synthesis of 3-alkoxymethylquinolin-2-ones may be carried out in a one-pot procedure directly from o-(vinylcarbonylamino)acylbenzenes. Aminomethylquinolin-2-ones are formed in one-pot approach only from corresponding o-(vinylcarbonylamino)benzophenones. Their analogs with o-alkyl-carbonyl groups form Michael adducts under these conditions.

Synthesis and some transformations of 2- and 2,2′-substituted bis(ethylenedioxy)biphenyls containing cyclopropane fragments

Abstract3,4: 3′,4′-Bis(ethylenedioxy)biphenyl undergoes bromination, nitration, and cyclopropylcarbonylation only at the 2-position. Analogous reactions with 2-substituted bis(ethylenedioxy)biphenyls occur regioselectively at the 2′-position. The reactions of 2-cyclopropylcarbonyl- and 2,2′-bis(cyclopropylcarbonyl)bis(ethylenedioxy)biphenyls with complex metal hydrides afforded the corresponding arylcyclopropylcarbinols which tended to undergo intramolecular alkylation of the aromatic ring with conservation of the cyclopropane fragment (monosubstituted derivatives) and formation of cyclopropyl-containing cyclic ethers (disubstituted ethylenedioxybiphenyls). The reduction of the nitro group in 2′-cyclopropylcarbonyl-2-nitro-4,5: 4′,5′-bis(ethylenedioxy)biphenyl was accompanied by intramolecular cyclization involving spatially close functional groups, the cyclopropane fragment remaining intact.

Heterocyclic Ions From N-Oxides of N-(4-Nitrobenzylidene)-2-cyclopropylaniline and N-(4-Nitrobenzylidene)-2-cyclopropylmethylniline: Formation, Isomerization, and Conversions

The N-oxide of N-(4-nitrobenzylidene)-2-cyclopropylaniline is converted by the action of strong acids into the corresponding 2,1-benzoxazinium derivative. Under identical conditions the N-oxide of N-(4-nitrobenzylidene)-2-cyclopropylmethylaniline forms the corresponding 2,1-benzoxazinium and 2,1-benzoxazepinium salts in a ratio of 1 : 2. The 2,1-benzoxazepinium ions are thermodynamically less stable and are isomerized with time into 2,1-benzoxazinium ions. Treatment of 2,1-benzoxazinium salts with hydrobromic acid solution and subsequent neutralization leads to o-(2-hydroxyalkyl)anilines and p-nitrobenzaldehyde. The effect of the nature of the ortho substituent on the direction of the conversions of the corresponding arylcyclopropanes is discussed.