Tetraphenylcyclopentadienones

C ( propyl) N phenylmtrone to N phenylmaleimide, 46, 96 semicarbazide hydrochloride to ami noacetone hydiochlonde, 46,1 tetraphenylcyclopentadienone to diphenyl acetylene, 46, 44 Alcohols, synthesis of equatorial, 47, 19 Aldehydes, aromatic, synthesis of, 47, 1 /3-chloro a,0 unsaturated, from ke tones and dimethylformamide-phosphorus oxy chloride, 46, 20 from alky 1 halides, 47, 97 from oxidation of alcohols with dimethyl sulfoxide, dicyclohexyl carbodumide, and pyndimum tnfluoroacetate, 47, 27 Alkylation, of 2 carbomethoxycyclo pentanone with benzyl chloride 45,7... 

Tetramethvlethylene, 47, 36 Tetraphenylcyclopentadienone, from dibenzyl ketone and benzil, 46, 45... 

The first reported example31,117 involved the diethyltetraphenyl-3//-azepines 18 and 19 which were obtained in 85% overall yield by the reaction of2,3-diethyl-2//-azirine with 2,3,4,5-tetraphenylcyclopentadienone (see Section 3.1.1.1.2.). The two isomeric azepines are separable by column chromatography (alumina or silica gel), and each isomer, on warming in xylene for three days, equilibrates to a 3 8 mixture of the 3//-azepines 18 and 19. 

Benzannulated azocines can be prepared starting from 4-phenyl-l,2.3-benzotriazine (16), flash-vacuum pyrolysis of which leads to 2-phenylbenzazete (17) (cf. Houben-Weyl. Vol. E16c, p 939), which is stable until about 40 °C and easily enters into cycloaddition reactions with dienes. With tetraphenylcyclopentadienone, a nonisolable adduct is formed which, by loss of carbon monoxide, gives an azabicyclo[4.2.0]octatriene derivative that isomerizes to the 1 -benzazocine 18.22... 

The reaction of tetraphenylcyclopentadienone (tetracyclone) with dialkyl phosphites has invoked further interest. Miller has shown that reactions at 20 °C in the presence of sodium bicarbonate lead to products (35) and (36), with phosphorus substituted at carbon rather than oxygen. Quite different products (37) and (38) are obtained at 160 °C, although whether (38) is obtained from initial attack at oxygen or carbon is still unresolved. 

Tetranitromethane as reagent for detecting double bonds, 21, 107 Tetraphenylcyclopentadienone, 23, 92, 93... 

This product is sufficiently pure for most purposes. It may be crystallized from a mixture of alcohol and benzene using 155— 160 cc. solvent for 5 g. of tetraphenylcyclopentadienone the melting point of the recrystallized material is 219-220°. 

Tetraphenylcyclopentadienone has been prepared by the action of phenylmagnesium bromide on benzaldiphenylmaleide,1 and by reduction, dehydration, and oxidation of the methylene-desoxybenzoin obtained by condensing formaldehyde with desoxy-benzoin.2 The present procedure is essentially that of Dilthey.3... 

Tetraphenylphthalic anhydride has been prepared by condensation of tetraphenylcyclopentadienone and maleic anhydride in nitrobenzene,1 followed by dehydrogenation of the tetraphenyl-dihydrophthalic anhydride with sulfur.2 3... 

Dimethylallene reacted with tetraphenylcyclopentadienone to produce methy-lenecyclohexadiene derivative 180 [146]. The cycloaddition occurred at the more substituted double bond of the allene, which was followed by extrusion of carbon monoxide from the intermediate 179. 

The yields of CO production in the reaction of BrFC with substituted benzaldehy-des are dependent on the electronic effects of para substituents. Carbonyl ylide intermediates were trapped with dimethyl acetylenedicarboxylate. Sterically hindered tetraphenylcyclopentadienone gave a high yield of CO and no ylide could be trapped in this case. 

Thiete sulfones show an irregular behavior pattern when involved in cycloaddition reactions. With 1,3-dienes, dienamines, enamines, ynamines, diazoalkenes, cyclopropadiene, and its substitution products, furan, and anthracene, the addition proceeds in the normal fashion. With certain Diels-Alder reagents such as tetraphenylcyclopentadienone (tetracycloneX however, the cyclic sulfones react anomalously. The Diels-Alder adducts undergo decomposition with SO 2 and CO extrusion to a seven-membered ring, the tetraphenylcycloheptatriene 223. Bicyclic octadienone is produced as well (Eq. 62). The mechanism of this unusual reaction is proposed by... 

Some unusual syntheses of substituted 2,2 -bipyridines deserve mention. Tetracyclone (tetraphenylcyclopentadienone) on heating with picolinonitrile at 215°C affords 3,4,5,6-tetraphenyl-2,2 -bipyridine, whereas 5-methyl-2,2 -bipyridine and some polysubstituted 2,2 -bipyridines are obtained by the oxidative degradation of the antibiotic streptonigrin. 5-Aldehydo-6-amino-2,2 -bipyridines are obtained by acid hydrolysis of pyrido[2,3-[Pg.311]

Cycloaddition of nitriles to tetraphenylcyclopentadienone gives an intermediate which by loss of carbon monoxide gives a pyridine, as shown in equation (74) (35CB1159,52MI20802). 

Is the - state likely to be higher or lower than the - state Explain in less than three lines. Is it plausible that compounds with this structure might be colored (recall tetraphenylcyclopentadienone) ... 

Diels-Alder addition of the benzazete (168) to tetraphenylcyclopentadienone (169) followed by CO loss yields the pentaphenylbenzazocine (170) (75JCS(PI)45). Intramolecular Wittig reaction of (171) gives some 3,4-dihydro-27/-benzoxocin (74JOC3038). 

A 100-ml., round-bottomed, ground-glass flask containing 40 g. of benzophenone is heated over a free flame to melt the bulk of the solid, and then 8.0 g. of tetraphenylcyclopentadienone (0.021... 

Other solvents tried and the liquid temperatures of the refluxing mixtures are stearic acid (340-365°), di- -butyl phthalate (320-325°), phenyl salicylate (290°). The first two solvents are unsatisfactory because of side reactions consuming some of the tetraphenylcyclopentadienone, the third because the addition reaction is too slow. 

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