2.6- diphenyl-4,4- - -perchlorate

A similar utilization of two heteroatoms is illustrated by the reaction of the ethylenedithiol (120) with formic acid in the presence of perchloric acid. 4,5-Diphenyl-l,3-dithiolylium perchlorate (121) was formed in 45% yield (69MI40300). Introduction of a 2-oxo or 2-thioxo substituent as in (123 X = 0, S) is illustrated by the reaction of the disodium salt (122) with phosgene and thiophosgene, respectively (76S489). 

Imidazolium halides pyrolysis, 5, 449 Imidazolium ions acylation, 5, 402 H NMR, 5, 352 hydrogen exchange, 5, 417 nucleophilic attack, 5, 375 reactivity, 5, 375 ring opening, S, 375 Imidazolium oxides in pyrrole synthesis, 4, 344 Imidazolium perchlorate, 1,3-diphenyl-acylation, 5, 402 Imidazolium salts 1-acetyl-... 

Stetter and ReischP described the preparation of 2,6-diphonyl-P5Tylium perchlorate (57) from l,5-diphenyl-2-penten-4-yn-l-one (56a) and concentrated sulfuric acid in the cold, followed hy perchloric acid, in 60% 5rield. The process may involve hydration to a 1,5-enedione, or an ion 56b related to 52, and valence tautomerism. 

On the other hand, 1,1,1-trisubstituted alkanes behave similarly to aldehydes, yielding pyrjdium salts (128) with identical substituents in positions 2 and 6. Thus, Dorofeenko and co-workers condensed 2 moles of acetophenone with 1 mole of benzotrichloride in the presence of perchloric acid obtaining 2,4,6-triphenjdpjTylium perchlorate with 1 mole of ethyl orthoformate, they obtained 2,6-diphenyl-pyrylium perchlorate (57) from o-hydroxyacetophenone, ortho-formic ester and perchloric acid, 4-ethoxybenzopyrylium perchlorate was formed. 

Certain dithiolium salts have been reported by Leaver and Robertson to form isothiazoles on treatment with ammonia thus, 3,5-diphenyl-l,2-ditholium perchlorate (15) gives a 50% yield of 3,5-diphenylisothiazole (16). The method does not appear to be generally applicable, and the analogous 3-methyl-5-phenyl-l,2-dithiolium salt did not give an isothiazole. 

Tlie smallest compounds among the azafulvalenes described to date are the azacalicenes, which are formed by combining a cyclopropenylidene moiety with a nitrogen-containing cyclopentadienylidene. Tlius, heating di-or triphenylpyrroles with diphenyl-methylsulfanyl-cyclopropenylium perchlorate in acetic acid gives the aza-triafulvalenium salts 33 and 34... 

Irradiating 7-substituted 2,4-diphenyl-6,7-dihydropyrido[2, l-n]phthalazi-nium perchlorates 62 in EtOH by 365 nm afforded pentacyclic derivatives 63 (94MI1). 

The three diazonium perchlorate isomers, and their 2-methyl-4,6-diphenyl analogues, all exploded on heating. 

The stereostructure of ethyl OT-4a,7-//-7-phenyl-8-cyano-2-oxo-2,3,4,4a,7,8-hexahydropyrido[l,2-A [l,2]oxazine-8-carboxylate was confirmed by X-ray crystallography. It confirmed a trans-nng junction <20000L4007>. The structure of 2,4-diphenyl-7-o-hydroxyphenyl-5,6-dihydropyrido[2,Ttf]phthalazinium perchlorate 21 has also been established by X-ray crystallographic analysis <1995IZV296>. 

The mechanism of the reaction is still obscure but our results are probably compatible with those of Pepper and Barton [23] who found that the rate of disappearance of unsaturation, when 1,3-diphenyl butene-1 (distyrene) reacted with perchloric acid, was of second order in olefin and in acid. Unfortunately they did not investigate whether any saturated products other than the cyclised dimer were formed, although they found some higher oligomers. 

Diphenyl-2,2 -bi(l,3-dithiol)-2/-yl-2-ylium perchlorate, 3746 Diphenylcyclopropenylium perchlorate, 3680... 

The Structure of a pyrido[l,2-6]cinnoline (17, R = Br) (74JHC125), a pyrido[2,l-a]phthalazine (26) (94T9189), and 2,4-diphenyl-7-o-hydroxyphe-nyl-5,6-dihydropyrido[2,l-fl]phthalazinium perchlorate (27) (95IZV296) have been established by X-ray crystallographic analysis. 

Phenoxanthin, 68 X = S Y = O, is prepared by the electrochemical oxidation of diphenyl ether in dichloromethane and trichloroacetic acid containing tetraethyl-ammonium perchlorate at a composite anode of carbon and sulphur. The anode generates sulphur cations, which carry out electrophilic substitution on the benzene ring [237], Phenoxathiin radical-cation, formed at the potential of the fust oxidation wave, has been characertised by esr spectroscopy [238],... 

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