6-Phenyl-2-hexyne

The intermolecular ortho photocycloaddition of acetylenes to benzene has provided routes to cyclooctatetraenes [78-84], Intramolecular photocycloaddition of alkynes to aromatic rings is also investigated. Morrison et al. reported that photolysis of 6-phenyl-2-hexyne in hexane solution using 254-nm light leads to the formation of bicyclo[6.3.0]undecatetraene (251 and/or 252) [284] (Scheme 70). Pirrung prepared various bicyclo[6.3.0]undecatetraenes (254a-e) by the in-... 

Intramolecular additions of a double bond to an aromatic nucleus have been reported. Chandross and Schiebel (148) have observed the Intramolecular addition of naphthalene to anthracene in 1-(9-anthryl)-3-(l-naphtyl)-propane. The reaction occurs presumably via an excited state complex between anthracene and naphtalene moeity. Morrison and co-workers studied the intramolecular addition of 6-phenyl-2-hexane [74] (74) and 6-phenyl-2-hexyne [75] (149). 

PROBLEM 15.37 The following IR spectra belong to 5-phenyl-1-pentyne and 6-phenyl-2-hexyne. Which is which Explain your reasoning. 

Eig. 7. CycHc voltammograms for the reduction of 1.0 mAf [2,2 -ethylene-bis(nitrilomethyHdyne)diphenolato]nickel(II) in dimethyl formamide at a glassy carbon electrode, in A, the absence, and B and C the presence of 2.0 and 5.0 mAf 6-iodo-l-phenyl-l-hexyne, respectively (14). 

In the presence of 6-iodo-l-phenyl-l-hexyne, the current increases in the cathodic (negative potential going) direction because the hexyne catalyticaHy regenerates the nickel(II) complex. The absence of the nickel(I) complex precludes an anodic wave upon reversal of the sweep direction there is nothing to reduce. If the catalytic process were slow enough it would be possible to recover the anodic wave by increasing the sweep rate to a value so fast that the reduced species (the nickel(I) complex) would be reoxidized before it could react with the hexyne. A quantitative treatment of the data, collected at several sweep rates, could then be used to calculate the rate constant for the catalytic reaction at the electrode surface. Such rate constants may be substantially different from those measured in the bulk of the solution. The chemical and electrochemical reactions involved are... 

Benkeser et al. (55) showed that a mole ratio of 2Cl3SiH to 1-hexyne would react completely in a long time. In 24 hours, a 98% yield of monoadducts had formed. After 111 hours, the same mixture yielded 20% 1,6-and 18% 1,2-bistrichlorosilylhexane. By increasing the concentration of catalyst, the yield of these two diadducts was increased to 44% and 40%, respectively. In this work, 1-trichlorosilyl-1-hexene behaved very much like 1-phenyl-l-hexene, shown in Table VI to form 1,6-diadducts. 

Dinuclear palladium complexes catalyze m-hydroarylation of alkynes with arenes.56 The reaction of 3-hexyne with benzene in the presence of a dinulear palladium complex Pd2R2(M-OH)(//-dpfam) [dpfam = j/V,Ar -bis[2-(diphenyl-phosphino)phenyl]formamidinate, R=/>-Tol] and tri(/z-butyl)borane at 100 °C for 4h affords ( )-3-phenyl-3-hexene quantitatively (Equation (53)). The hydroarylation of 3-hexyne with monosubstituted benzenes ( )-3-aryl-3-hexenes with a 2 1 ratio of the meta- and ra -isomers. This regioselectivity is different from that of the hydroarylation of diphenylacetylene catalyzed by Rh4(GO)12.57... 

Several publications deal with acetylenic halides that can undergo reductive intramolecular cyclization [37]. For example, electrolysis of 6-iodo-l-phenyl-l-hexyne at a carbon cathode gives benzylidenecy-clopentane in 36% yield. 

H2PtCI6 PdCl2 1 1 Copolymer of 2,3-bis(diethylphosphine)-1,3-butadiene and maleic anhydride 1-Hexyne Isoprene Phenyl acetylene 81... 

Maleimede, N-phenyl-, 41, 93 Malonitrile, condensation with tetra-cyanoethylene, 41, 99 Mercuric oxide in preparation of catalyst for conversion of 2,5-di-methyl-3-hexyne-2,5-diol to 2,2,5,-... 

Ethylenedioxybutyl)-3-trichloro-acetamido 1 cyclohexene, 58, 9, 11 Ethylene, 1,1-diphenyl-, 56, 32 Ethylene glycol, 56, 44 Ethylene glycol, phenyl-, 55, 116 Ethylene, tetramethyl-, 56, 35 Ethyl-or-fluoro-l-naphthaleneacetate, 57, 73 Ethyl 2-fluoropropanoate, 57, 73 3-Ethylhexane, 58, 3, 4 3-ETHYL-1-HEXYNE, 58,1, 2, 3, 4 Ethyl levuhnates, 5-substituted, 58, 81 Fthyl nitrite, 58, 113, 115 Ethyl V-nitroso-A-fp-tolylsulfonylmethyl)-carbamate, 57, 96 3-Ethyl-3-pentanol, 58, 25, 26, 31 3-Ethyl-3-pentyl alcohol, 58, 78 3-Ethyl-3-pentyl fluoride, 58, 78 Ethyl A -(p-tolylsulfonylmethyl)carbamate, 57, 95... 

This appears to be the first report of the addition of H2 to the silylformyla-tion reaction mixture. Good yields are obtained when Et3SiH or PhjSiH is used in the reaction of 1-hexyne or 4-phenyl-l-butyne. Although a variety of functionally substitued terminal alkynes have been studied, most lead only to the silylformylation product and do not appear to be affected by the presence of H2 in the system. Other rhodium catalysts investigated, such as [Rh(COD)(dppb)]+BPh4 and Rh6(CO)16, catalyze the silylformylation reaction even under H2 pressure and do not lead to any of the silylhydrofor-mylated products. 

FLUORINECOMPOUNDS,ORGANIC - FLUORINATED AROMATIC COMPOUNDS] (Vol 11) 6-Iodo-l-phenyl-l-hexyne... 

Over the zeolites mentioned above, acetophenone and propiophenone are easily and quantitatively produced from the hydration of phenyl acetylene and 1-phenylpropyne in very short periods of time, whatever zeolite is used. This result is in agreement with the special high reactivity of phenyl acetylene and derivatives towards hydration already found in homogeneous catalysis (ref.6). On the other hand, 1-hexyne and 2-hexyne, which are known to be less reactive towards hydration, are converted into the corresponding hexanones in relatively convenient yields. For example, over HM (Si/A1=8), 30% 2-hexanone is produced from 1-hexyne after one hour reaction. 

Reaction of pentacarbonyl[phenyl(methoxy)carbene ]chromium with 1-hexyne ... 

The kinetics and stereochemistry of addition of HC1 to 1-phenyl-propyne and to 3-hexyne in acetic acid have been found to be different in the two cases (4 and 5 of Table 2) (Fahey and Lee, 1966,1967,1968). 

The kinetics of the cyclization reaction of 5-hexynyllithiums 19 was also studied showing that (6-phenyl-5-hexynyl)lithium (19, R = Ph) has a half-life of ca 6 min at —50.6 °C, whereas cyclization reaction of 5-decynyllithium (19, R = Bu) is some 106 times slower. The rather dramatic increase in the rate of cyclization on going from an alkyl-substituted 5-hexyn-l-yllithium to a phenyl-substituted substrate is most likely a consequence of a reduction in A// due to stabilization of the incipient vinyllithium product by the phenyl group19. It is also interesting to note that the 5-exo-dig cyclization reaction of 19 (R = Bu) is slower than the corresponding 5-exo-trig carbolithiation reaction of 5-hexenyllithium. 

Trimethylsilylphenylsilylene also reacts with disubstituted acetylenes such as 3-hexyne, 1-trimethylsilylpropyne, bis(trimethylsilyl)acetylene, and 2,2,5,5-tetramethyl-3-hexyne to give the respective silacyclopro-penes. The silacyclopropenes thus formed, with the exception of 1,2,3-tris(trimethylsilyl)-l-phenyl-l-silacyclopropene, can be distilled under reduced pressure without decomposition. 

Photolysis of a hexane solution of 20 in the presence of 3-hexyne gives l-trimethylsilyl-l-phenyl-2,3-diethyl-l-silacyclopropene which can be isolated in pure form by distillation followed by preparative GLC. 

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