Cyclopropenone, diphenyl-, reaction with

In contrast, methyl cyclopropenone is reported283) to react with the Pt-olefin complex 455 at low temperature with replacement of the olefin ligand. In the resulting complex 456 the cyclopropenone interacts with the central atom via the C /C2 double bond according to spectroscopic evidence284). At elevated temperatures a metal insertion to the C1<2)/C3 bond occurs giving rise to 457. Pt complexes of a similiar type were obtained from dimethyl and diphenyl cyclopropenone on reaction with 455 and their structures were established by X-ray analysis285). 

One of the first syntheses of a triafulvene utilized the Wittig reaction, when diphenyl cyclopropenone was reacted with triphenyl carbomethoxymethylene phos-phorane giving 696 ) ... 

Diphenylcyclopropene thione (156) was prepared11S-12°) from 3,3-dichloro-1,2-diphenyl cyclopropene (154) by reaction with thioacetic acid, since transformation of the carbonyl function of diphenyl cyclopropenone with P4S10121 was complicated by ring expansion to the trithione 155122 In a useful recent thioketone synthesis123) 156 was obtained directly from diphenyl cyclopropenone in a quantitative yield by simultaneous treatment with HC1 and H2S. 

Substituted cyclopropenones such as the diphenyl derivative undergo cycloaddition reactions with activated dienes either by [4 + 2] or [4 + 3] modes. For example, N-1,3-butadienyl-N,N-diethylamine adds to diphenylcyclopropenone via the normal [4 + 2]... 

Both dipropyl-]125] and diphenyl-[26,139] -cyclopropenones take part in dipolar cycloaddition reactions with diazomethane, the final products being pyridazones, e.g. 

Reaction of diphenyl eyelopropenone with phosphorus pentasulphide converts it into diphenylcyclopropenethione [119], Similar conversions of cyclopropenones into cyclopropenethiones have also been accomplished. using thioacetic acid in the presence of tetrafluoro-boric acid or perchloric acid [151]. ... 

The Wittig reaction of diphenyl cyclopropenone with the phosphorane 68 failed to give the methylene cyclopropene instead a hydrocarbon of probable structure 67 was obtained71. ... 

The reaction of diphenyl cyclopropenone with aryl malononitriles75 or aryl cyano acetone84 unexpectedly gave rise to 4-cyano-4-aryl triafulvenes 90, as well as the formation of quinocyclopropenes (see later) ... 

Oxidation of diphenyl or di-tert. butyl cyclopropenone with wi-chloro peroxy-benzoic acid207 proceeds via intermediates corresponding to a Bayer-Villiger-type mechanism 277/278) to unrearranged products (1,2-diketones) or rearranged products (ketones) depending on the reaction conditions. 

A rather complex reactivity towards the cyclopropenone system is exhibited by N-nucleophiles. Thus, ammonia reacts with diphenyl cyclopropenone to yield either the enamino aldehyde 323222> or a mixture of the cis and trans isomeric diphenyl azetidinones 522223 depending on the reaction conditions these products result from primary addition of the nucleophile at C,(2 ... 

This is further accentuated by the surprising results of the reaction between aziridine and diphenyl cyclopropenone which was elucidated by Dehmlow224. In aprotic media two molecules of aziridine react with a cyclopropenone moiety eliminating ethylene and forming enamino amide 527, whereas in protic media one molecule of aziridine reacts with the exclusive formation of the aziridide 326 ... 

Finally, a reaction should be mentioned in which a nucleophile gives support to another reacting species without appearing in the final product. Diphenyl cyclopropenone interacts with 2,6-dimethyl phenyl isocyanide only in the presence of tri-phenylphosphine with expansion of the three-ring to the imine 344 of cyclobutene-dione-1,2229,230 Addition of the isocyanide is preceded by formation of the ketene phosphorane 343, which can be isolated in pure formss 231 it is decomposed by methanol to triphenyl phosphine and the ester 52. 

The bicyclic enamine 383 deviates from the above reaction scheme when interacting with diphenyl cyclopropenone the betaine 384 formed initially does not iso-merize to the amide 385, but to the a-amino cyclopentenone 386, possibly favored by steric reasons248. ... 

N-Heteroaromatic compounds like pyridine, pyridazine, pyrazine, isoquinoline, and their derivatives42,250 react with diphenyl cyclopropenone in a formal (3+2) cycloaddition mode to the C=N bond of the heterocycle. As expected from the results discussed earlier (p. 67), the reaction is initiated by attack of nitrogen at the cyclopropenone C3 position and followed by stabilization of the intermediate betaine 390 through nucleophilic interaction of the Cl/C3 bond with the activated a-site of the heterocycle, giving rise to derivatives of 2-hydroxy pyrrocoline 391—394). In some cases, e.g. diphenyl cyclopropenone and pyridine42, further interaction with a second cyclopropenone molecule is possible under the basic conditions leading to esters of type 392. 

Pyridinium, phosphonium, arsonium and sulfonium acyl ylides all react with diphenylcyclopropenone to give 3,4-diphenyl-a-pyrones (equation 61) These reactions are assumed to be initiated by attack of the acyl oxygen on the cyclopropenone. 

The condensation reactions of cyclopropenones provide a simple and effective method for the synthesis of stable calicenes. Thus, 2,3-diphenyl- and 2,3-dialkylcyclopropenones 8 slowly react with 1,2,3,4-tetrahalocyclopenta-l,3-diene in methanol at around room temperature to precipitate yellow crystals of l,2,3,4-tetrachloro-5,6-diphenylcalicene (9, R = Ph) and colorless crystals (e.g., when R = Pr) of 5,6-dialkyl-l,2,3,4-tetrahalocalicenes 9in moderate yields. "... 

In the reaction of 3,3-pentamethylenediaziridine 116 with diphenyl-cyclopropenone the C—N—N moiety can add either to the carbonyl group, to give 123, or to the ring-opened cyclopropenone to give 124. ... 

Reaction of pyrazines with diphenylcyclopropenone provides a useful synthesis of 7,8-diphenyl-substituted compounds. Thus pyrazine reacts with two molecules of the reagent to give the acryloyl ester 37 in 31% yield. 2,6-Dimethylpyrazine reacts with one molecular equivalent of the reagent to give an 80% yield of the hydroxy compound 8 on standing with the cyclopropenone in methanol for three days at room temperature. Similarly cycloheptenocyclopropenone reacts with 2,6-dimethylpyrazine to give the tricyclic system 38. It has been assumed that 2-methylpyrazine reacts with both cyclopropenones to give the less hindered compounds 39 rather than the isomers 40. 

---