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Grignard reagents (R2MgBr; R2 = Me, p-tolyl) regioselectively attacked the α-carbon of the bridgehead double bond of methyl- and benzylazafulleroids (only R2 = Me) in contrast to the β-carbon attac...

Novel single electron transfer (SET) reaction of dienamine with C60 is presented. The generated dienamine radical cation underwent a 1,6-hydrogen shift followed by a radical–ion coupling with a C60...

Palladium-catalyzed hydrogenolysis of gem-diphenylcyclopropanes fused with trihalogenobenzoquinones gave diphenylmethylhydroquinones. Water took part in the reaction to yield α-hydroxydiphenylmethyl- and benzoylhydroquinones. The selective ring-cleavage was interpreted in terms of the π-conjugative interaction of cyclopropane.

Reaction of phenyldiazomethane (1) with tetrafluoro-1,4-benzoquinone (2a) gave isomeric mixtures of stilbenes (3, cis/trans=4.7) and spirooxetanes (4a, cis/trans=1.1) via zwitterion intermediates. Similarly, tetrabromo-1,4-benzoquinone (2c) provided 3 and spirooxetane (4c); however, the cis/trans ratio of 3 dropped to 2.3 and 4c was solely the trans isomer. On the other hand, reaction with tetraiodo-1,4-benzoquinone (2d) afforded no spirooxetane and gave a further reduced isomer ratio of 3 of 1.9.

2,3-Dichloro-5,6-dicyanobenzoquinone (DDQ) reacted with diazoethane to give stereoisomeric bicyclic diones (3, isomer ratio=3.4) arising from dipolar addition to the C=C bond of DDQ. DDQ reacted with phenyldiazomethane to afford also stereoisomeric bicyclic diones (7) in the ratio of 5:1, together with stilbenes (8). On the other hand, DDQ gave the (ethenyloxy)benzene derivative (14) with 1-phenyldiazoethane. The formation of 8 and 14 was interpreted by considering the participation of 1:1 betaines resulting from addition to the C=O bond. The added methanol captures the betaines, thus giving rise to dimethyl acetals of benzaldehyde and acetophenone, along with 2,3-dichloro-5,6-dicyanohydroquinone. These reactivities of DDQ were discussed in comparison with those of chloranil.

Substituted diphenyldiazomethanes[(x-C6H4)2CN2; x=p-OCH3, p-CH3, H, p-Cl] were found to react with 2,5-dichloro-p-benzoquinone at its conjugated C=C and C=O bonds to give bicyclic diones and poly(2,5-dichlorohydroquinone benzhydryl ether)s respectively, obeying the second-order kinetic law. The product ratios of the polyethers to the bicyclic diones increased from 1.1 to 8.1 with the electron-donating ability of the substituents. The individual rate constants were well correlated with the Hammett equation: logk3=−2.15–1.55 σ (r=0.996) and logk4=−2.03–1.85 (σ0+0.515Δ\barσR+) (r=1.00) for the bicyclic diones and polyethers processes respectively. The presence of methanol as a trapping agent stopped the polymerization completely and afforded the methanolysis product, though no essential change was found in the formation of the bicyclic dione.

The kinetics and products of the reactions of fifteen meta- and para-substituted diphenyldiazomethanes with chloranil were investigated in tetrahydrofuran. The second-order rate constants, k, increased with the electron-donating ability of the substituents, and the values could be correlated with the Yukawa-Tsuno equation: logk⁄k0=−1.67(σ0+0.66Δ\barσR+)+0.009, (r=0.996). The ρ value, −1.67, indicates the large development of a positive charge at the diazo carbon in the transition state, while the R value, 0.66, confirms the considerable stabilization of the positive charge by the π-electronic contribution of the para substituents. The products of these reactions were the corresponding 2,3,5,6-tetrachlorohydroquinone poly(benzhydryl)ethers, but these polyethers were easily hydrolyzed into the corresponding benzophenones and tetrachlorohydroquinone(HQ). On the other hand, the initial presence of water or methanol as an additive changed the reaction features to give benzophenone or α,α-dimethoxydiphenylmetha...

The reactions of several aryldiazomethanes (1a: p-tolyl; 1b: phenyl; 1c: p-chlorophenyl) with chloranil gave stilbenes (3) and spiro-oxetanes (4) at 20 °C in tetrahydrofuran or 1,2-dichloroethane. The isomer ratios of 3 were ca. 2 to 3:1 in favor of cis, depending on the solvents and on the substituents of 1. In the case of 4, however, stable trans-isomers were selectively formed. On the other hand, the presence of added CH3OH suppressed the formations of 3 and 4 and, instead, induced redox reactions giving α,α-dimethoxyarylmethanes and tetrachlorohydroquinone (6). In these redox reactions, the acid decompositions of 1 with 6 were also found. However, the presence of CF3CH2OH allowed the formation of considerable amount of 3 and 4, along with the redox products. The mechanism of these reactions will be discussed.

Unsubstituted 1,4-benzoquinone (1a) reacted with diphenyldiazomethane (DDM) at the C=C double bonds to give dihydroxy-3H-indazole (2a) and its benzhydryl ether (3a) together with benzodipyrazole derivative (4a). Similarly, reactions of 2-chloro- and 2,3-dichloro-1,4-benzoquinones (1b and 1c) with DDM yielded the corresponding dihydroxy-3H-indazoles (2b, 2b′, and 2c) and their benzhydryl ethers (3b, 3b′, and 3c) along with 5–13% benzophenone (6). On the other hand, reaction of 2,6-dichloro-1,4-benzoquinone (1e) with DDM gave bicyclic 5e and tricyclic diones (7e), together with benzophenone dimethyl acetal (9) in the presence of added methanol. In the same conditions, 2,3,5-trichloro-1,4-benzoquinone (1f) provided bicyclic dione (5f) and 9. Formation of 6 and 9 was interpreted as arising from the hydrolysis and methanolysis of the 1:1 betaine intermediates given by the addition of DDM to the quinonoid C=O double bonds. The C=O addition increased with increasing chlorine substituents.

A stereochemical study was made of the reaction of phenyldiazomethane(1) with chloranil(2) at 20 °C in 28 aprotic solvents. The products were trans-spirooxetane(4) and cis-trans mixtures of stilbene(3) (ca. 2–5 times cis-rich). The molar ratios of cis-3 to the sum of the trans-3 and 4 tended to increase, whereas the 4 to trans-3 ratios decrease with the increase in the solvent basicity and polarity. These effects of solvents on the product distributions were interpreted in terms of the effects of the solvent basicity and polarity on the stereoselective formation of the diazonium betaine intermediate and on the conformational isomerism. Moderately successful linear-free-energy(LFE) relationships were established for these product ratios with the aid of the combination of the empirical solvent basicity parameter, Dπ, and the Kirkwood function, f(e), or ET values as the solvent polarity parameters.

Kinetic studies have been made of the reactions of fifteen meta- and para-substituted diphenyldiazomethanes(DDMs) with 2,3-dichloro-5,6-dicyanobenzoquinone(DDQ) in benzene. The second-order rate constants, k, increased with the electron-donability of the substituents, and the value could be correlated with the Yukawa-Tsuno equation: logk⁄k0=−2.33(σ0+0.47Δ\barσR+)+0.017, (r=0.996,30 °C). The ρ value, −2.33, indicates the development of a positive charge at the diazo carbon in the transition state, while the R value, 0.47, confirms the moderate stabilization of the positive charge by the π-electronic contribution of the para substituents. The rate constants have also been determined for the reaction of diphenyldiazomethane(DDM) with DDQ in 28 aprotic solvents. The effects of solvents can be interpreted in terms of the basicity and the steric nature of the solvents. The products of these reactions were poly(2,3-dichloro-5,6-dicyanohydroquinone benzhydryl ether)s, which were easily convertible into benzopheno...

A kinetic study was made of the reactions of diphenyldiazomethane (DDM) with chloranil and 2,5-dichloro-p-benzoquinone (DCQ) at 30 °C in 20 and 22 aprotic solvents respectively (19 solvents are common). The chloranil reaction gave poly(tetrachlorohydroquinone benzhydryl ether) alone, obeying the second-order kinetic law. On the other hand, the DCQ reaction afforded bicyclic dione and poly(2,5-dichlorohydroquinone benzhydryl ether), also obeying the second-order kinetic law. All these rate constants generally increased with the solvent polarity and decreased with the solvent basicity. The kinetic solvent effects can be interpreted in terms of the effects of the polarity and the basicity of the solvents respectively to the transition and to the initial states. Thus, the multiple liner correlations of the logarithmic rate constants with a suitable function of the polarity and the basicity of the solvents are fairly successful. It was found that the basicity is more pronounced in the chloranil reaction than i...

Unsubstituted 1,4-benzoquinone (1a) reacted at the C=C double bond with 9-diazofluorene (9-DF) to give norcarene dione 2a and 4,7-dihydroxy-3H-indazole 4a. Similarly, the reaction of 2-chloro-1,4-benzoquinone (1b) with 9-DF yielded norcarene dione 2b and 4,7-dihydroxy-3H-indazole 4b, together with tricyclic dione 3b. 2,3-dichloro-1,4-benzoquinone (1c) and 9-DF produced norcarene dione 2c, 4,7-dihydroxy-3H-indazole 4c, and its fluorenyl ether 5c. Reactions of 2,5- and 2,6-dichloro- and trichloro-1,4-benzoquinones (1d, 1e, and 1f) with 9-DF provided norcarene diones 2d, 2e, and 2f and tricyclic diones 3d and 3e, respectively. On the other hand, tetrachloro-1,4-benzoquinone (1g) converted 9-DF into 9,9′-bifluorenylidene possibly via a 1:1 betaine intermediate arising from the C=O double bond addition. These results were markedly different from those of the previous diphenyldiazomethane reactions and are discussed in terms of structural changes of these diazoalkanes.

It was found that a number of diazoalkanes (I) bearing a relatively small substituent reacted with o-sulfobenzoic anhydride (II) in acetonitrile at an ordinary temperature to give the o-(substituted glycoloyl)benzenesulfonic acid sultones (IV), which correspond formally to the products from the insertion into the C–O bond of II by the carbenes, while diaryldiazomethanes underwent decomposition under the same conditions to produce the corresponding tetraarylethylenes (V) instead of the inserted products (IV). The olefin formation reaction was very fast compared to the sultone formation and was considered to be the result of the acid-catalyzed decomposition caused by the contaminant o-sulfobenzoic acid (III) which was derived from II. The kinetics and the mechanism of these reactions were discussed on the basis of the nature of diazoalkanes.

Eight 2,2-diaryl-1,3-dioxanes were prepared and the kinetic substituent effects regarding acidcatalyzed hydrolysis were studied in 80% dioxane–water(v/v) at 30 °C. The logk were well correlated with the Yukawa-Tsuno equation; logk⁄k0=−2.92(σ0+0.385Δ\barσR+)(r=0.999).

Reactions of phenyldiazomethane with chloranil and of 1-phenyldiazoethane and 9-diazofluorene with 2,3-dichloro-5,6-dicyano-p-benzoquinone in the presence of oligoethylene glycols and its monomethyl ethers gave the corresponding substituted crown ether acetals and open-chain analogues.