Reaction of substituted 7-cyclopropyl-1,4-benzodioxanes with dinitrogen tetraoxide

The reaction of 6-bromo-7-cyclopropyl-1,4-benzodioxane with N₂O₄ in methylene chloride does not affect the cyclopropane ring and forms the nitrodebrominated product (ipso-substitution). The same reaction of 6-nitro- and 5,6-dinitro-7-cyclopropyl-1,4-benzodioxanes produces only the products with an modified threemembered ring. The difference in the reaction paths of the studied cyclopropylbenzodioxanes with N₂O₄ is explained by the different ratio of substrate to one-electron oxidant, the nitrosyl cation.M. V. Lomonosov Moscow State University, Moscow 119899Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 324–329, March, 1999.     

6-Cyclopropyl- and 6-(1-methylcyclopropyl) 1,4-benzodioxanes: synthesis and nitration. Rearrangement of nitro substituted 6-cyclopropyl-1, 4-benzodioxanes using concentrated sulfuric acid

6-Cyclopropyl- and 6-(1-methylcyclopropyl)-1,4-benzodioxanes have been synthesized as the first cyclopropyl 1,4-benzodioxanes. It was shown that nitration of these compounds occurs with retention of the three carbon ring. In contrast to simple ethers of cyclopropylphenols, nitration leads only to 7-nitro-6-cyclopropyl- and 7-nitro-6-(1-methylcyclopropyl)-1, 4-benzodioxanes,respectively. Nitration of 7-nitro-6-cyclopropyl-1,4-benzodioxane occurs regioselectively to give exclusively the 7 8-dinitro product. The structure of the nitration products was confirmed by their rearrangement to the corresponding nitrosopropionyl-1,4-benzodioxanes.M. V. Lomonosov State University, Moscow 119899. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 472–479, April, 1994. Original article submitted February 2, 1994.     

Photopromoted carbonylation of 1-bromo-6-chlorohexane under ambient conditions

Photopromoted carbonylation of 1-bromo-6-chlorohexane with CO catalyzed by CuBr2 and CdI2 has been carried out under ambient conditions. The results indicate that the carbonylation proceeds with the major product of chloroester ClCH2（CH2）5COOCH3 under catalysis of CuBr2. Furthermore, the activity of the carbonylation can be improved by addition of basic additives （NaOAc, Na3PO4 or （n-C4H9）3N）. Among these additives, （n-C4H9）3N is the most efficient in terms of the yield of ClCH2（CH2）5COOCH3. However, the methoxycarbonyl substituting chlorine product of BrCH2（CH2）5COOCH3 is not obtained in the presence of CdI2. This is quite different from the carbonylation of monochloroalkane.     

Design and synthesis of coumarinyl 1,4-benzodioxanes as potential anti-oxidant

A series of novel coumarinyl 1,4-benzodioxanes were successfully synthesized from electronically diverse 2-[(o-iodophenoxy)methyl]oxiranes and different positional isomers of hydroxycoumarin via one-pot tandem nucleophilic displacement and copper-mediated intramolecular C–O coupling reaction using CuI and 1,10-phenanthroline as the efficient catalytic system. All the compounds were characterized by ¹H, ¹³C NMR, IR, HRMS spectra and a selected set of newly synthesized compounds offered noticeable in vitro free hydroxyl radical scavenging activity in a systematic dose dependent manner which signifies their excellent biological potential.     

Synthesis of 2,3,8,9-Dibenzo-5,6-(substituted)benzo-1,4-dithio-7-oxacyclonona-2,5,8-trienes and some electrophilic substitution reactions

Treatment of 5-(2-hydroxyaryl)thianthreniumyl perchlorates 1 with sodium hydride in tetrahydrofuran at reflux gave the title compounds 5 in excellent yields. For the reactivities of the compounds 5 , the selected compounds 5 were subjected under the conditions of electrophilic substitution reactions. Bromination of 5,6-{3-(2-butyl)benzo}-2,3,8,9-dibenzo-1,4-dithio-7-oxacyclonona-2,5,8-triene ( 5f ) in acetic acid at 60° afforded two bromo compounds 9 (22%) and 10 (69%), which were oxidized by m-chloroperbenzoic acid to give tetraoxides 11 (95%) and 12 (97%), respectively. Treatment of 5f with acetyl chloride in the presence of aluminum chloride in carbon disulfide at 0° gave an acetylated compound 13 (58%). Nitration of 5f with nitric acid in acetic acid at 50° gave a nitro compound 17 (15%) together with 1,4-dioxide 7e (22%) and a 5-oxide 18 (3%) whose regiochemistry has not been established. On the other hand, 5,6-(3-methylbenzo)-2,3,8,9-dibenzo-1,4-dithio-7-oxacyclonona-2,5,8-triene ( 5a ) reacted with acetyl chloride under the same conditions to give two acetylated compounds 15 (33%) and 16 (18%). The mechanism for the formation of 5 and the structural elucidation of these compounds are discussed.     

The preparation of ethyl 7-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-5-methyl-4-oxo-1,8-naphthyridine-3-carboxylate

Ethyl 7-Chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-5-methyl-4-oxo-1,8-naphthyridine-3-carboxylic acid has been prepared by a route involving masking of the C_2,3 double bond through reduction, followed by regioselective deprotonation of the C₅ position and methylation and then regeneration of the C_2,3 double bond via selenation, oxidation, and syn-elimination.     

Behavior of an alkylthioacetaldehyde under conditions of the Mannich reaction

Conclusions Alkylthioacetaldehydes under the conditions of the aminomethylation reaction give-alkylthioacro-leins, which under the synthesis conditions are dimerized to 2-formyl-2,5-dialkylthio-2,3-dihydro--pyrans.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2516–2519, November, 1972.     

Behavior of semicarbazones under the conditions of the Fischer reaction

Cyclohexanone semicarbazone and phenylsemicarbazone form 1,2,3,4-tetrahydro- and 1,2,3,4,5,6,7,8-octahydrocarbazoles under the conditions of the Fischer reaction. The reaction proceeds through a cyclohexanone azine intermediate. The product of oxidation of the azine is oxidized by air oxygen to 1,2,3,4-tetrahydrocarbazole. The investigated semicarbazones are stable with respect to the action of sodium ethoxide at up to 300°C.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1487–1489, November, 1978.     

Synthesis and reactions of 7-substituted 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids as an antibacterial agent

1-Cyclopropyl- and 1-ethyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acid derivatives having a sulfinyl or sulfonyl group at C-7 were synthesized from 2,6-dichloro-5-fluoronicotinic acid derivatives by the route involving the Dieckmann-type cyclization. The displacement reactions of these compounds with pyrrolidine and piperidine gave mainly the 7-(1-pyrrolidinyl)- and 7-(1-piperidinyl)-1,8-naphthyridine derivatives 24-27 , respectively. Enoxacin, a potent antibacterial agent, was also synthesized with the analogous route.     

Synthesis and antibacterial activity of new 5-substituted 1-cyclopropyl-6-fluoro-7-piperazinyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids

The 5-hydroxymethyl and the 5-formyl-1-cyclopropyl-6-fluoro-7-piperazinyl-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxylic acids have been prepared via a 5-trimethylsilyl group and were tested in vitro as potential antibacterials.     

PEG 400 promoted nucleophilic substitution reaction of halides into organic azides under mild conditions

Abstract

Polyethylene glycol 400 (PEG 400) has been demonstrated as an efficient and eco-friendly reaction medium for the preparation of organic azides from structurally diverse halides by nucleophilic substitution reaction with NaN₃ under mild conditions. The advantages of this protocol are: operational simplicity, environmental safety, broad substrate scope, excellent functional group tolerance, and short reaction time. The PEG 400 can be recovered and reused.     

Electrophilic substitution of 5- and 6-substituted benzo-1,4-dioxanes

The compositions of the products of bromination, nitration, and acetylation of 5- and 6-fluoro(chloro, nitro, methoxy, methyl, formyl, and carboxy)benzo-1,4-dioxanes were established. The reactivity indexes and the characteristics of the UV spectra of the starting compounds were calculated by the self-consistent-field (SCF) MO LCAO method within the Pariser-Parr-Pople (PPP) and CNDO/2 CI (complete neglect of differential overlap with configuration interaction) approximations, and the results were compared with the experimental data.Translated from Khimiya Geterotsiklicheskikh Soedinenii,No. 11, pp. 1465–1471, November, 1978.     

Green synthesis of glycerol 1,3-bromo- and iodohydrins under solvent-free conditions

ABSTRACT

New eco-friendly conditions for Finkelstein reaction employing homogeneous media or alumina-supported reagents, both solventless, were utilized in the bromohydrins and iodohydrins synthesis from 1,3-dichlorohydrin (1,3-DCH), obtained from glycerol. Thus, the trans-halogenation of glycerol-1,3-dichlorohydrin (1) in homogeneous media, using NaI, NaBr salts and organic additives (TBAI, TBAB), led to the synthesis of four different glycerol halohydrins (2a, 2b, 3a, 3b) in regular to excellent conversions (43–96%) and good selectivities to 3a and 2b. Already, the alumina-supported reagents such as KI, KBr, NaBr were used for glycerol-1,3-dichlorohydrin trans-halogenation, in the absence of solvent, producing halohydrin mixtures in high conversions (77–99%) and very good selectivity (82%) to 1,3-diiodo-2-propanol (2b).     

Rationalization of regioselectivity of electrophilic substitution reaction for cyclic compounds in terms of Dpb values

Accepted theories predict that substitution reactions are controlled by the electronic nature of the attacked site for electrophilic aromatic substitution. Here it is shown that in addition the bond strength of the broken bond may also influence the regioselectivity of the substitution reaction, and that the Dpb is a good indicator of the strength of a chemical bond. The Dpb denotes the depth of the potential acting on one electron in amolecule at the bond center (bc). In this letter, the values of Dpb along the C-H and N-H bonds have been investigated, and it is demonstrated that for aromatic compounds, the regioselectivity of the electrophilic substitution can well be rationalized in terms of Dpb values.