2-Carboxybenzenediazonium chloride

Benzyne generated from 2-carboxybenzenediazonium chloride reacted with sulfur monochloiide to give dibenzothiophene 13 (8-10%) and thiantherene 14 (26-35%) (1989SUL83). A mechanism involving the addition of sulfur mono-chloride to benzyne with the formation of betaine 15 followed by the elimination of SCI2 to afford benzothiirene 16 and a further reaction with another benzyne molecule or dimerization to thianthrene 14 is given in Scheme 8. 

Reaction of l,3-benzodithiole-2-selone 228 with benzyne (obtained from 2-carboxybenzenediazonium chloride 229 as precursor) in refluxing 1,2-dichloroethane afforded the sulfonium salt 9a77-9-selena-10-thia+b-thioniain-deno[l,2- ]indene chloride 118 CP in 82% yield (Equation 48) <1996BCJ2349>. 

A series of thiiranes react with benzyne to provide an efficient synthesis of phenyl vinyl sulfides. The reaction is stereospecific, thus producing ds-(phenylthio)stilbene from ds-2,3-diphenylthiirane and tra s-(phenylthio)stilbene from (ram-2,3-diphenyl thiirane (Scheme 30) (84TL2679). 2-Car-boxybenzenediazonium chloride and benzenediazonium-2-carboxylate provide a clean source of benzyne. A mixture of 2-carboxybenzenediazonium chloride (a source of benzyne), a thiirane, and... 

Benzyne and substituted benzynes, generated by thermal decomposition of 2-carboxybenzenediazonium chloride or by aprotic diazotization of appropriate anthranic acids, reacted with a variety of thiophene dioxides to produce naphthalene derivatives generally in moderate yields (Scheme 56) [34,159]. In two cases, the naphthalenes so produced further reacted with benzyne to give benzobarrelene derivatives. 

Benzyne generated from 2-carboxybenzenediazonium chloride cleaves cyclic and acyclic sulfides, as in the conversion of thiolane 609 to 613. Apparently protonation to the sulfonium salt 612 is faster than cleavage of intermediates 610 and/or 611. 

The same concept has been extended to the synthesis of aromatic and heteroaromatic compounds bearing two 1-adamantyl substituents <90JA5654> and two neopentyl substituents <94TL2709> at ort/io-positions. Interestingly, the reaction of 3,4-dineopentylthiophene-1,1-dioxide with benzyne (from 2-carboxybenzenediazonium chloride) gives (217) as the major product (68%) via an ene reaction the cycloadduct-S02 extrusion product (218) is formed in 20% yield. The latter undergoes further cycloaddition with another molecule of benzyne to give a dibenzo barrelene derivative (7.5%). The formation of such barrelene derivatives had been observed earlier with a few other thiophene-1,1-dioxides as well <86H(24)1233>. 

Styrene oxide and benzyne are reported to give the 1 1 adducts 35 and 36 (9% and 6% yield, respectively), both derived from the same intermediate 34.36 However, propene oxide is apparently unreactive to benzyne, since its use is advocated to react with the hydrogen chloride which is released when benzyne is generated by decomposition of o-carboxybenzenediazonium chloride (Section II,B).37 37a-b... 

If benzyne was generated instead from o-carboxybenzenediazonium chloride in the presence of 108, the remarkable siloxepine 111 was formed (>70%) its structure was confirmed by X-ray diffraction.79 It was shown that the intermediate 1 1 adduct 110 reacts with benzenediazonium-2-car-boxylate (4) at a lower temperature than is required for the decomposition 4 -+ 5 -+ 1 (Scheme 1) this step includes the formation of the strong Si—O bond, and subsequent loss of nitrogen and cyclization lead to 111. The germanium analog of 111 was similarly obtained from 109. 

Carbon suboxide, 52 Carbonylation, 148, 149, 216 Carbonyl chlorofluoride, 48, 54 Carbonyl cyanide, 60-61 N,N -Carbonyldiimidazole, 61 1,1-Carbonyldi-l,2,4-triazole, 61 N-Carbonylsulfamic acid chloride (N-Carbonylsulfamyl chloride), 61 Carboxamides, 270 Carboxamine-N-sulfochlorides, 70 p-Carboxybenzenediazonium chloride, 62 p-Carboxybenzenesulfonazide, 62 Carboxylation, 15, 16 Carboxylic acid anhydrides, 133 Carboxylic acid N,N-dimethylamines, 153 Carboxylic anhydrides, 409-410 p-Carboxyphenylhydrazones, 62 Cardenolides, 130, 131 (S-Carotene, 19 /-Carvone, 451, 452 i//-Caryophyllene, 149, 150 Catechol, 65, 233 Catechol amines, 159 Catechyl phosphorus tribromide, 63 Catechyl phosphorus trichloride, 63 Cis-Cecropia juvenile hormone, 261 Cedrene, 234, 235 a-Cedrene, 349 /3-Cedrene, 349 Cendranoxide, 234, 235 Cephalosporin C, 48 Ceric ammonium nitrate, 63-65 Ceric sulfate. 65 Cesium fluoride, 346 trans-Chalcone oxide, 422 Chalcone phenylhydrazones, 257, 258 Chalcones, 406 Chloramine, 65-66, 69 Chloranil, 66-67, 113, 116, 401,454... 

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