1,3-Butadiene 1.2.3.4- tetraphenyl

In the reduction of trienes, only the central double bond was hydrogenated (equation 48)125. The product was a cis,cis-, 3-butadiene derivative. Similar results were obtained in the hydrogenation of the tetraphenyl derivative with a Pd catalyst modified... 

In the stannole series, the reactions could be explained by the extraordinary reactivity of the exocyclic tin-carbon bonds with regard to lithium reagents. Thus, the reaction of 1,4-dilithio-1,2,3,4-tetraphenyl-1,3-butadiene with 1,1 -dialkyl-2,3,4,5-tetraphenylstannole leads to alkyl-tin bond cleavage-cyclization by the dilithium reagent33 (equation 61). 

CpLuCl2(THF)2 reacts with 2 equiv. of Na[PhCH= CHPh] in DME with dimerization of the stilbene radical anions to form [Na(DME)3][Cp2Lu /u.-CH(Ph)CH(Ph)-CH(Ph)CH(Ph) ] containing a dianionic 1,2,3,4-tetraphenyl-butadiene ligand. X-ray crystal structure determination shows Lu coordinated to two Cp rings and the dianionic butadiene ligand in an rj and 1,4-diyl fashion. ... 

The configuration of all the previously described double Diels -Alder adducts has not been determined, although addition of the second diazene group to the cyclohexadiene moiety of the intermediate adducts is expected to occur anti to the cyclohexadiene substituent. In fact, a single an/7-bisadduct 6 was isolated from the reaction of 1,1,4,4-tetraphenyl-1,3-butadiene and 4-phenyl-3//-l,2,4-triazole-3,5(4//)-dione and the structure was inferred from H- and 13C-NMR studies10. 

In contrast to earlier interpretations gas phase decarbonylation of ionized 2,3,4,5-tetraphenyl-2,4-cyclopentadienone (147) does not result in the formation of an ionized tetraphenyl-substituted tetrahedrane (148), but yields exclusively the isomeric cyclo butadiene derivative (149) (Scheme 24). 

Figure 4. Substrates that can react with four atoms of Li to give tetralithium tetraanions (A) 1,2,3,4-tetraphenyl-l,3-butadiene , (B) 5,5-dimethyl-l,2,3,4-tetraphenyl-5-silacyclopentadiene , (C) octalene , (D) 9,9 -bianthryl , (E) acepleiadylene .

Germylene-bridged rac-[(1,2,3,4-tetraphenyl-1,3-butadiene-1,4-diyl)germylene-bis(indenyl)] zirconium dichloride 1188 was synthesized using the salt metathesis approach.918 When combined with A1Bux3 and Ph3C[B(C6F5)4],... 

The Reppe hydrocarboxylation of acetylenes was initially carried out in the presence of an acid, but little was known about the function of the acid or the nature of the carbon monoxide transfer agent. Sternberg et al. found that diphenylacetylene can be hydrocarboxylated in alkaline solution and that in this case a nickel carbonyl anion is the source of carbon monoxide. When the hydrocarbon was shaken with a saturated solution of sodium hydroxide in methanol in the presence of excess nickel carbonyl under helium the reaction mixture turned dark red. After 80 hrs., acidification and workup aiforded a-phenyl-rru/is-cinnamic acid and 1,2,3,4-tetraphenyl-butadiene in the yields indicated. Note that the ciimamic acid results from cis addition of the elements of formic acid. 

Show the most likely product from a Diels-Alder reaction of 4 with 1,3-butadiene. Pay attention to all relevant aspects of stereo- and regioselectivity (recall your laboratory chemistry with the tetraphenyl derivative). 

So liefert die nicht selektive Belichtung von 2,3-Diphcnyl-butadien (I A = 254 nm in 2,2,4-Trimethyl-pentan) ein kompliziertes Reaktionsgemisch, welches 1,2,5,6- Tetraphenyl-cyclooctadien-(l,5) (II) enthalt1 ... 

Mit Aryl-substituierten konjugierten Dienen liefert Natriumamalgam unter Isomerisie-rung l-Aryl-2-alkene. So bildet 1-Phenyl-1,3-butadien l-Phenyl-2-buten (70% d.Th., Kpi4 73°) und l,l,4,4-Tetraphenyl-l,3-butadien 1,1,4,4-Tetraphenyl-2-butens (F 141°) ... 

Partial hydrogenation of cumulenes affords m-polyenes selectively in the presence of the Lindlar catalyst (a palladium-calcium catalyst deactivated by lead acetate see p. 19) hydrogenation ceases almost entirely after a rapid absorption of (n — l)/2 moles of hydrogen (n = number of double bonds). According to Kuhn and Fischer,139 tetraphenylbutatriene absorbs one equivalent of hydrogen, yielding l9l9494-tetraphenyl-l93-butadiene ... 

Isoprene and particularly 2,3-dimethylbutadiene react more readily than butadiene itself. 1,4-Diphenyl- and 1,2,3,4-tetraphenyl-butadiene require temperatures in excess of 200°, and loss of HC1 begins already under these conditions so that the phospholes (3) are obtained directly without isolation of the phospholene dihalides.45... 

Treatment of the reaction mixture, first with methanol and then with water, led to an organic solution, whose usual chromatographic separation and spectral identification showed the presence of only diphenylacetylene and (E,E)-1,2,3,4-tetraphenyl-1,3-butadiene (mp 181.5-183 °C) (16). 

Competitive Cyclizing and Noncyclizing Dimerizations. When reactions such as noncyclizing dimerization were prolonged for 40-50 h, then 1,2,3-tri-phenylnaphthalene (mp 148-150 °C), (Z,Z)-1,2,3,4-tetraphenyl-l,3-butadiene (mp 146-148 °C), and (E)-l,2-diphenylethene (mp 124-125 °C) could be isolated from the hydrolyzed reaction mixture by column chromatography on aluminum oxide and elution with a benzene-hexane gradient. The principal product was still the (E,E)-1,2,3,4-tetraphenyl-l,3-butadiene. 

Long-Term Interaction with Lithium in THF. A solution of 12.21 g (69 mmol) of diphenylacetylene in 30 mL of THF was stirred at 20-25 °C with 80 mg (11 mg-at) of lithium pieces for 140 h. Upon hydrolytic workup, 150 mg of a light-brown solid was obtained, which was insoluble in water, benzene, and acetone. This product was subjected to sublimation at 180-200 °C under 0.01 mmHg for 3 days. The colorless sublimate was identified as hexaphenylbenzene by IR and melting-point comparisons. The organic layer contained preponderantly diphenylacetylene and some (E,E)-1,2,3,4-tetraphenyl-l,3-butadiene (16). 

Interception of (E,E)-l, 2,3,4-Tetraphenyl-l, 3-butadiene. A suspension of 4.30 g (1.56 mmol) of (Cod)2Ni in 30 mL of THF was cooled to 0 °C, and then a solution of 5.55 g (31.2 mmol) of diphenylacetylene in 30 mL of THF was added dropwise over 15 min. A red solution resulted, and stirring was continued for another 15 min. Then 30 mL of 6 N DC1 in DaO was added, the mixture was exposed to air as it rose to 25 °C, and then ethyl ether was added to extract the organic products. The organic extract was washed thoroughly with water, dried over anhydrous MgS04, and evaporated in vacuo. The residue was subjected to column chromatography on neutral aluminum oxide with an eluent gradient of benzene-hexane. A 2.0-g recovery of diphenylacetylene was obtained (36%), and 276 mg of (E,E)-1,2,3,4-tetraphenyl-l, 3-butadiene was isolated (5%). By NMR and MS measurements, (E,E)-1,2,3,4-tetraphenyl-l,3-butadiene was shown to be dideuterated at the 1,4-vinylic positions. Some hexaphenylbenzene was recovered from the top of the column (23). 

---