Toshikazu Nagai

Stereochemistry of the copper perchlorate or copper bromide-catalyzed decomposition of aryldiazomethanes to stilbenes

Several phenyldiazomethanes easily decompose to cis- and trans-stilbenes when treated with catalytic amounts of copper perchlorate or copper bromide at 20°C. The preferential formation of cis isomer is particularly noteworthy. The stereochemistry and the mechanism of these reactions will be discussed.

Reaction of vinylcarbenoids with benzaldehydes: formation of vinylcarbonyl ylides followed by ring closure to oxiranes and dihydrofurans.

Rh2(OAc)4-catalyzed reaction of vinyldiazo compound 1a in the presence of p-methoxybenz- 2a, mesit- 2b, and p-chlorobenzaldehyde 2c gave a mixture of isomeric vinyloxiranes 3a−c and 4a−c, and sterically unstable (E)-dihydrofurans 5a−c, but not stable (Z)-dihydrofurans 6. However, the reactions with p-nitro- 2d and 2,4-dinitrobenzaldehyde 2e gave (Z)-dihydrofurans 6d,e along with 3d, 4d, and 5d,e. The reaction in the presence of maleic anhydride and dimethyl fumarate gave single 1,3-dipolar cycloadducts 11 and 13, respectively, indicating that a single conformer, the sterically unstable endo-aryl-endo-cyanostyryl carbonyl ylide 14 (15), is initially formed in the reaction of 1 with 2. It was concluded that the endo-vinyl-exo-aryl vinylcarbonyl ylides 17a−c arising from 2a−c undergo disrotatory cylization to exlusively produce 5, whereas the ylides 17d,e arising from 2d,e undergo partly symmetry-forbidden conrotaory cyclization to sterically stable trans-diaryldihydrofurans 6d,e as well as the symmetry-allo...

Reactions of alkanesulphonic acid derivatives with organoalkali metal compounds : Formation and reactivity of α-sulphonylcarbanions

Abstract The effects of solvents, metals and structural variation of the substrates on the reactions between alkanesulphonic acid derivatives with organoalkali metal reagents have been examined and the formation and reactivity of α-sulphonylcarbanions are discussed. The formation of 4-membered cyclic sulphones from a sulpbonyl fluoride and the Claisen ester condensation type reaction in a sulphonic ester, which have been observed for the first time, are described.

The reaction of benzylsulfonyl halides with phenyllithium: Preparation of sulfones

Abstract The reactions of benzylsulfonyl halides with phenyllithium have been studied. The reaction of benzylsulfonyl chloride with phenyllithium in diethyl ether at 20–25° gave lithiumbenzyl sulfinate as a main product, in addition to other eight products. While the reaction of benzylsulfonyl fluoride with phenyllithium under a similar condition afforded a disulfone, α-benzylsulfonyl-α-benzenesulfonyltoluene, as a major product. On the other hand, the reactions at a low temperature (−80°) yielded a polysulfone which did not form when the reactions were carried out at an ordinary temperature. The differences of reaction courses due to a difference of a halogen content or an experimental condition are discussed, and probable mechanisms of these results are presented.

Reaction of vinylcarbenoids with aldehydes: formation of vinylcarbonyl ylides followed by ring closure to oxiranes and dihydrofurans

Rh(2)(OAc)(4)-catalyzed reaction of vinyldiazo compound 1a in the presence of p-methoxybenz- 2a, mesit- 2b, and p-chlorobenzaldehyde 2c gave a mixture of isomeric vinyloxiranes 3a-c and 4a-c, and sterically unstable (E)-dihydrofurans 5a-c, but not stable (Z)-dihydrofurans 6. However, the reactions with p-nitro- 2d and 2,4-dinitrobenzaldehyde 2e gave (Z)-dihydrofurans 6d,e along with 3d, 4d, and 5d,e. The reaction in the presence of maleic anhydride and dimethyl fumarate gave single 1,3-dipolar cycloadducts 11 and 13, respectively, indicating that a single conformer, the sterically unstable endo-aryl-endo-cyanostyryl carbonyl ylide 14 (15), is initially formed in the reaction of 1 with 2. It was concluded that the endo-vinyl-exo-aryl vinylcarbonyl ylides 17a-c arising from 2a-c undergo disrotatory cylization to exclusively produce 5, whereas the ylides 17d,e arising from 2d,e undergo partly symmetry-forbidden conrotaory cyclization to sterically stable trans-diaryldihydrofurans 6d,e as well as the symmetry-allowed process to 5d,e.

Facile synthetic methods of acetals and crown ethers from the reaction of diphenyldiazomethane with 2,3-dichloro-5,6-dicyanobenzoquinone in the presence of alcohols

Abstract The reaction of diphenyldiazomethane with 2,3-dichloro-5,6-dicyano-benzoquinone in the presence of alcohols and thiols gave the corresponding benzophenone acetals and thioacetals at 20–25°C in 1,2-dichloro-ethane. The mechanism of the reaction will be discussed.

The reactions of 1,4-bis[α-diazobenzyl]benzene with sulfur dioxide

Abstract The reactions of 1,4-bis[α-diazobenzyl]benzene (I) with sulfur dioxide in aprotic solvents below ordinary temperature give the oligomer II of p -xylylidene type and 1,4-dibenzoylbenzene (III). The ratio of II to III increases with the increasing polarity of solvent in the order of petroleum ether, benzene, and tetrahydrofuran. While the reaction in the presence of water or methanol yields 1,4-bis[α-sulfobenzyl]benzene (VIII) or 1,4-bis[α-methoxysylfonylbenzyl]benzene (VII) respectively. These results appear to show that the present reactions proceed via a sulfene intermediate.

The reaction of anthracene with sulfur dioxide in the presence of benzoyl peroxide : The formation of anthracene sulfones

Abstract The reaction of anthracene with SO2 in the presence of benzoyl peroxide using n-heptane as solvent, yielded anthronyl phenyl sulfone, oligomers (anthracene polysulfones), diphenyl disulfone, benzenesulfonic acid, anthraquinone, benzoic acid and benzene. If benzene was used as solvent, the formation of the sulfones mentioned above was not observed, and instead the reaction yielded 9,10-dibenzoyloxyanthracene, dianthrone, anthraquinone, benzoic acid and a trace of benzene-sulfonic acid. These results have been interpreted in terms of a C-T complex1 of anthracene-sulfur dioxide, since the sulfones are readily formed in a solvent such as n-heptane which does not interact with SO2, whereas the formation of the sulfones is diminished in a solvent such as benzene due to its interaction with SO2.2 As in the reaction of SO2 with benzoyl peroxide using n-heptane as a solvent, diphenyl disulfone, benzenesulfonic acid, benzoic acid, benzene, phenyl benzoate and diphenyl disulfide were isolated; the yields of diphenyl disulfone, benzenesulfonic acid and diphenyl disulfide being derived from the phenylsulfonyl radical were larger than those obtained from the reaction with anthracene, the phenyl radical readily reacts with SO2 in the absence of anthracene, but the formation of the phenylsulfonyl radical is diminished in the presence of anthracene. And these results might be interpreted in terms of the interaction of anthracene with SO2 rather than with the phenyl radical, because phenylanthracene derivatives did not form but some anthracene sulfone was obtained.

Xanthylium salts from thermolysis of diphenylcyclopropanes fused with bromo-substituted 1,4-benzoquinones

Abstract Thermolysis of diphenylcyclopropanes fused with bromo-substituted 1,4-benzoquinones resulted in the formation of xanthylium salts via ring opening accompanied by 6π electrocyclization.

Reaction of 1-phenyldiazoethane with tetrachloro-p- and o-benzoquinones

Abstract Reaction of 1-phenyldiazoethane(1) with tetrachloro- p -benzoquinone(2) gave 1-alkoxy-4-ethenyloxy-tetrachlorobenzene(4). With tetrachloro- o -benzoquinone(5), 1 provided 1-alkoxy-2-ethenyloxy-tetrachlorobenzene(7) and tetrachlorobenzo-1,3-dioxolane(8). The mechanism and the effect of added methanol were discussed.