Bicyclic allenes : Generation and trapping of 6,7-benzobicyclo [3.2.1] octa-2,3-diene

Treatment of 3-bromo-6,7-benzobicyclo [3.2.1] octa-2,3-diene (9) with potassium tert.-butoxide produces the strained bicyclic allene (10) which is trapped by 1,3-diphenylbenzo[c]furan (DBI) to give five isomeric cycloadducts. In the absence of DBI, allene (10) gave rise to enol ether (18) by addition of tert.-butanol.     

EDA Complexes of 2,3-Dichloro-1,4-naphthoquinone with Some Substituted Anilines

Summary. Electron donor-acceptor (EDA) complexes of several substituted anilines with the -acceptor 2,3-dichloro-1,4-naphthoquinone (DClNQ) in chloroform, dichloromethane, and 1,2-dichloroethane were studied by a spectrophotometric method. Experimental data has been shown to confirm the 1:2 stoichiometry of the acceptor-donor in spite of the apparent linearity of the Benesi-Hildebrand plot for a 1:1 complex. The calculated values of oscillator strengths, transition moments, and thermodynamic parameters confirms the 1:2 (A:D) stoichiometry of the complexes. The formation constants and molar absorptivities for these AD₂ complexes have been evaluated. The stoichiometry was unaffected by the variation of the temperature over a small interval and also by the change in polarity of the solvent. The order of the donor strength followed the sequence: N-benzylaniline>p-chloroaniline>m-chloroaniline>o-chloroaniline.Present address: Materials Research Centre, Indian Institute of Science, Bangalore-12, India     

EDA Complexes of 2,3-Dichloro-1,4-naphthoquinone with Some Substituted Anilines

Electron donor-acceptor (EDA) complexes of several substituted anilines with the -acceptor 2,3-dichloro-1,4-naphthoquinone (DClNQ) in chloroform, dichloromethane, and 1,2-dichloroethane were studied by a spectrophotometric method. Experimental data has been shown to confirm the 1:2 stoichiometry of the acceptor-donor in spite of the apparent linearity of the Benesi-Hildebrand plot for a 1:1 complex. The calculated values of oscillator strengths, transition moments, and thermodynamic parameters confirms the 1:2 (A:D) stoichiometry of the complexes. The formation constants and molar absorptivities for these AD₂ complexes have been evaluated. The stoichiometry was unaffected by the variation of the temperature over a small interval and also by the change in polarity of the solvent. The order of the donor strength followed the sequence: N-benzylaniline>p-chloroaniline>m-chloroaniline>o-chloroaniline.     

A spectrophotometric study of molecular complexes of 2,3-dicyano-1,4-naphthoquinone

Molecular complexes of 2,3-dicyano-1,4-naphthoquinone with various aromatic anilines were studied spectrophotometrically in dichloromethane solvent at different temperatures. All these complexes show a new broad charge-transfer band in the visible region of the electromagnetic spectrum. All the donors are known to form strong 1:1 complexes with the acceptor and their stoichiometry was unaffected by the variation of temperature over a small interval. The thermodynamic and spectroscopic parameters were evaluated. The order of donor strength followed the sequence: 2,5-dimethylaniline > 2,3-dimethylaniline > N,N-dimethylaniline > p-toluidine > o-toluidine > m-toluidine > N-methylaniline > aniline.     

Reactions of Substituted Indoles with 2,3-Dichloro-1,4-naphthoquinone and Electrochemical Properties of Some 2,3-Substituted 1,4-Naphthoquinones

Russian Journal of Organic Chemistry - The reactions of 2,3-dichloro-1,4-naphthoquinone with some indoles and thiols were investigated. The resulting nucleophilic substitution products were...     

Interaction of 2,3-dichloro-1,4-naphthoquinone with n-butylamine in halocarbon solvents

The rapid interaction between 2,3-dichloro-1,4-naphthoquinone (DClNQ) and n-butylamine results in the formation of 2N(n-butylamino)-3-chloro-1,4-naphthoquinone as the final product. The reaction is found to proceed through the initial formation of charge-transfer (CT) complex as an intermediate. The final product of the reaction has been isolated and characterized using FTIR, H1 and C13 NMR spectroscopy, mass spectrometry, and elemental analysis. The rate of formation of product has been measured as a function of time in different halocarbon solvents, viz., chloroform, dichloromethane and 1:1 (v/v) mixture of two solvents. The pseudo first order and second order rate constants at various temperatures for the transformation process were evaluated from the absorbance time data. The activation parameters (E(a), DeltaS#, DeltaH#, and DeltaG#) were obtained from temperature dependence of rate constants. The influence of dielectric constant on the properties of reaction was discussed and the probable course of reaction is presented.     

Electron donor-acceptor interaction of 3,4-dimethylaniline with 2,3-dicyano-1,4-naphthoquinone

The electron donor–acceptor (EDA) interaction between 2,3-dicyano-1,4-naphthoquinone (DCNQ) and 3,4-dimethylaniline (3,4-DMA) is studied in chloroform, dichloromethane and 1:1 (v/v) mixture of chloroform and dichloromethane. The rate of formation of the product was measured as a function of time using UV–vis spectrophotometer. The formation constant (K) and molar extinction coefficient (?) values for the formation of EDA complex were evaluated in the temperature range of 20–35 °C. The pseudo-first-order rate constant (k₁) and the second-order rate constant (k₂) for the disappearance of EDA complex and for the formation of product were evaluated. The activation parameters (ΔH^#, ΔS^# and ΔG^#) of the reaction were determined by temperature dependence of rate constants using the Arrhenius plots. The effect of relative permittivity of the medium on the reaction is discussed. The observed results indicate that formation of final product proceeds through initial formation of EDA complex as an intermediate. The product of the reaction was purified by column chromatography method and identified as 3-(N-3,4-dimethyl-phenylamino)-2-cyano-1,4-naphthoquinone by elemental analysis, IR and NMR spectroscopy. On the basis of kinetic, analytical and spectroscopic results, a plausible mechanism for the formation of EDA complex and its transformation into product is proposed.     

Generation and trapping of 6,6-dimethyl-6-silafulvene

Flow pyrolysis of allylcyclopentadienyldimethylsilane and of 1-dimethylmethoxysilyl-1-trimethylsilylcyclopentadiene afforded 6, 6-dimethyl-6-silafulvene which was either trapped or allowed to dimerize.     

A reexamination of the reactions of 2,3-dichloro-1,4-naphthoquinone with thioamides

2,3-Dichloro-1,4-naphthoquinone reacts with thioamides and thiourea to give mixtures of condensed thiazoles and thianthrenes.     

Reaction of 2,3-Bis(benzotriazol-1-yl)-1,4-naphthoquinone

Russian Journal of General Chemistry -     

Reaction of N1, N2-diarylamidines with chloranil and 2,3-dichloro-1,4-naphthoquinone

Nucleophilic attack by N² of N¹ N²-diarylformamides 1a-c on C-2 of chloranil (2) and subsequently by N¹ on C-1 of 2 initiates the formation of benzimidazolinones 8a-c. In contrast, when 1b-e is reacted with 2,3-dichloro-1,4-naphthoquinone (9) , both chlorine atoms are successively substituted by the two nitrogen atoms and 2-(arylamino)-3-(N-formylarylamino)-1,4-naphthoquinones 13b-e result, which (probably via their cyclic tautomers 12b-e ) may be cyclodehydrogenated to form N¹,N³-diarylnaphtho[2,3-d] imidazoline-2,4,9-triones (as 14b,c ). On the other hand, N¹,N²diarylacetamidines 15a-d attack 2 and 9 at C-2 with N² but subsequently exert nucleophilic character at the acetamidine α-carbon attacking C-1 of 2 and 9 , respectively, thus forming 1-aryl-2-(arylimino)-3a-hydroxy-2,3,3a,6-tetrahydro-1N-indol-6-ones 18a-d and 3-aryl-2-(arylimino)-9b-hydroxy-2,3,5,9b-tetrahydro-1-H-benz[e]indol-5-ones 19b,c , respectively. The latter may be thermally dehydrated to the fully conjugated 2,5-dihydro-3H-benz[e]indol-5-ones 20b,c. Unambiguous structural assignments for 18b and 20c are made on the basis of X-ray crystal structure analyses.     

Generation and cycloaddition reactions of indole-2,3-quinodimethanes

N-methyl and N-tert-butoxycarbonylindole-2,3-quinodimethanes ($\text{2}$ and $\text{3}$) have been generated and observed to undergo intermolecular cycloaddition reactions with dienophiles.     

Generation of mono- and bis-dioxiranes from 2,3-butanedione

Biacetyl reacts with oxone to give bis-dioxirane [3,3'-dimethyl-3,3'-bidioxirane, 3B] and mono-dioxirane [1-(3-methyl-dioxiran-3-yl)ethanone, 3A)]. Bis-dioxirane 3B is formed when two oxygens are incorporated into biacetyl, while mono-dioxirane 3A incorporated only one. A greater stability is observed in 3B compared to 3A, which is attributed to an alpha-dioxiranyl (anomeric) effect in the former. In contrast, 3A suffers from a destabilizing pi-electron withdrawing effect from the adjacent carbonyl group.