Journal of Chemical Research

Phenanthrene-9,10-quinone reacts with anisole in the presence of SnCl₄.5H₂O at 180 °C to give 11-methoxybenzo[b] phenanthro[9,10-d]furan and with veratrole to form both the 11,12-dimethoxy and the 10-monomethoxy analogues.

A two-phase catalysed dehydrogenation synthesis of acyldiazenes from acylhydrazines using 2,4,6-tri-t-butylphenol/Fe(CN)₆^3-/NaOH is reported.

A short and facile synthesis of a series of 2,3,4,5-tetrahydro-1H-1,3,4-benzotriazepine-5-one derivatives was accomplished in good yields via the intermolecular reductive coupling reaction of 2-nitrobenzoic hydrazides and aldehydes or ketones promoted by the low-valence titanium reagent (TiCl₄/Zn system). Structures were established on the basis of elemental analysis, IR and ¹H NMR spectra.

A simple and enviromentaly benign method for synthesis of flavones is described via dehydrative cyclisation of o-hydroxydibenzoylmethane using silica gel supported NaHSO₄ catalyst.

Primary aryl amines reacted with aryl halides to give the secondary aryl amines by the catalysis of [Pd(dba)₂/P(t-Bu)₃] at 80 °C in toluene. Secondary aryl amines reacted with 1-bromo-pyrene and 9-bromo-phenanthrene and 2,7-dibromo-9H-fluorene to afford the OLED material of aminopyrene derivatives and aminophenanthrene derivatives and diamino-9H-fluorene type by the catalysis of [Pd(OAc)₂/P(t-Bu)₃] at 120 °C in o-xylene. The product structures were established by ¹H NMR, ¹³C NMR, ¹³C(DEPT), HRMS spectra. Physical properties were examined by UV-vis, PL and DSC spectra.

N-Phenylanthranilic acid derivatives were synthesised using the Ullmann condensation of 2-chlorobenzoic acid with aniline derivatives under microwave irradiation in aqueous media. The method offers better yields in shorter reaction times compared to classical heating approaches using water as solvent.

4-Bromo-3-formyl-1,2-dihydronaphthalenes undergo Suzuki cross coupling and Wittig olefination reaction in a one pot procedure. The trienes obtained can be cyclised thermally under concomitant dehydrogenation to dihydrophenanthrothiophenes and dihydrophenanthro[1]benzothiophenes. An X-ray crystal structural analysis was carried out for ethyl (E)-3-[1-(1-benzothiophen-3-yl)-3,4-dihydro-2-naphthyl]propenoate.

Various enolic compounds such as acetyl acetone, ethyl- and methyl-acetoacetate condense with 2-hydroxy-2, 2′-biindan-1,1′,3,3′-tetrone 1 in acid medium to produce adducts, which preferentially remain in the hemi-ketal form as confirmed by X-ray diffraction studies. 1 is also found to undergo acid catalysed dimerisation to furnish a cage like adduct fabricated by ketal and hemi-ketal linkages.

O-Alkylation of the flexible tetrathiacalix[4]arenes 1 with 4-(chloromethyl)pyridine in the presence of Cs₂CO₃ gave tetra-O-alkylated products with 1,3-alternate and 1,2-alternate conformation.

1-substituted 7-chloro-6-fluoro-4-oxo-1,2-dihydroquinoline-3-carboxylic acids were converted to borate complexes. These compounds were treated with piperazine in presence of triethylamine to afford ciprofloxacin and norfloxacin in high yields.

Condensation of 5a,6-dihydro-5a,6,6-trimethyl-2-nitro-12H-indolo[2,1-b][1,3]benzoxazine derivatives with ortho-hydroxy-substituted aromatic aldehydes afforded 1′-(2-hydroxy-5-nitrobenzyl)spiro[1-benzopyran-2,2′-indoline].

Hydromagnesiation of alkylarylacetylenes 1 in diethyl ether gave (E)-α-arylvinyl Grignards reagents 2, which reacted with arylsulfenyl chlorides 3 to afford stereoselectively (E)-1,2-disubstituted vinyl sulfides 4 in good yields.

A series of isothiocyanates have been prepared in high yields in a one-pot reaction from commercial amines and carbon disulfide under mild conditions using bis(trichloromethyl)carbonate (BTC) and trichloromethyl chloroformate (TCF) as reagents in the presence of base.

A new class of phosphorus macroheterocycles (4a–j) has been synthesised in two steps. The reaction of 1 mole of 3,4-diamino-1,2,5-oxadiazole (1) with 2 moles of aqueous formaldehyde gave a Schiff's base which subsequently underwent addition with 2 moles of 4-t-butylphenol in 1,4-dioxane, afforded N,N-bis-(5-t-butyl-2-hydroxybenzyl)furazan-3,4-diamine (2). Cyclisation of 2 in situ with various substituted aryl phosphorodichloridates (3a–j) in the presence of Et₃N in THF afforded 13-membered macroheterocycles (4a–j) containing P, N, O and C in good yields.

DABCO–POCl₃ was found to be an efficient reagent for the dehydration of aldoximes to nitriles under mild reaction conditions in excellent yields.

Cycloaddition of 3-(4-acetylphenyl)sydnone (1) with DMAD gave dimethyl 1-(4-acetylphenyl)-1H-pyrazole-3,4-dicarboxylate (2), which on bromination yielded the corresponding monobromoacetyl (3) and dibromoacetyl (4) derivatives. Both compounds 3 and 4 on reaction with thiourea and thioacetamide afforded the 2-amino- (5) and the 2-methyl- (6) thiazole derivatives respectively, while compound 3 on reaction with 2-aminothiazole gave the imidazothiazole 7. Compound 3 was converted into its azide (8), which on 1,3-dipolar cycloaddition with DMAD afforded the 1,2,3-triazole-4,5-dicarboxylate (9).

Acylbenzotriazoles were found to react with substituted hydrazines and aqueous hydrazine under very mild conditions, thus affording a facile synthesis of three types of acylhydrazines in moderate to excellent yields.

The condensation of o-phenylenediamines with both aliphatic (acyclic and cylic) and aromatic ketones has been carried out to produce 1,5-benzodiazepines in high yields using perchloric acid adsorbed on silica gel as a heterogeneous catalyst. The catalyst can be recycled.

In this paper the preparation of 3,3,6,6-tetramethyl-9-aryl-1,2,3,4,5,6,7,8,9,10- decahydroacridin-1,8-dione derivatives from aromatic aldehydes, 5,5-dimethyl-1,3- cyclohexanedione and ammonium acetate in ionic liquids [bmim⁺][BF₄^-] is described. This new method has the advantages of easier work-up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods.

A simple and efficient method for the synthesis of unsymmetric trisannelated benzenes is presented. The dimers of cycloketones react with molecules of other cycloketones to form corresponding unsymmetric trisannelated benzenes in the presence of thionyl chloride in anhydrous ethanol.

A simple, efficient and eco-friendly method has been developed for the condensation of hydroxylamine hydrochloride with aldehydes, ketones and 1,3-diketones in the presence of powdered molecular sieves (3Å) as catalyst. Aldoximes, ketoximes and 1,3-dioximes were obtained in excellent yields.

The bromination reactions of isomeric 7,8-dibromobenzobicyclo[2.2.2]octa-2,5-dienes were studied and the possible role of neighbouring groups in rearrangements was investigated. Bromination of endo-cis dibromide 9 gives only the rearranged product 14 while the reaction of the exo-cis-dibromide 11 under the same conditions gives only non-rearranged products 15, 16 and 19. The possible role of substituents in the rearrangements was discussed.

Several 2,4-dialkyl-3,5-bis(arylimino)-1,2,4-thiadiazolidines were synthesised under mild conditions in good yield by the selective oxidation of N-alkyl-N'-arylthioureas by using 1-(4-diacetoxyiodobenzyl)-3-methyl imidazolium tetrafluoroborate [dibmim]⁺[BF₄]^- in ionic liquids.