Trans 1-Phenyl 1,3 butadiene

Butadiene, 1-phenyl-, trans-, 7S Butane, 1,4-diiodo-, 33 -Butylacetylene, is Butyl alcohol, 19, 20 -Butyl bromide, 16 -Butyl iodide, 34... 

C54H40CI7S, 1-(2,6-Dichlorophenyl)-4-phenyl-trans,trans-1,3-butadi-ene l-(2,6-dichlorophenyl)-4-(2-thienyl)-trans,trans-1,3-butadiene (2,5 1 mixed crystal), 45B, 108 C79H68CI2N2O14S2, Isopropylidene-bis-4,4 -(diphenylcarbonate) bis(2,5-diphenyl-4-p-dimethylaminophenylthiapyrylium perchlorate), 44B, 333... 

Phenyl-1,4-hcxadicnc (122) is obtained as a major product by the codimerization of butadiene and styrene in the presence of a Lewis acid[110]. Pd(0)-catalyzed addition reaction of butadiene and aiiene (1 2) proceeds at 120 C to give a 3 1 mixture of trans- and c -2-methyl-3-methylene-l,5.7-octatriene (123)[lll]. 

A study [19] of the cycloaddition between substituted (E)-l-phenyl-1,3-butadienes 55 and substituted 1,1-dicyanoethylenes 56 leading to cis- and trans-cyclohexenes 57 and 58 (Equation 5.8) has shown that diastereoselectivity is markedly dependent on pressure. 

The [2+ 2]-cycloadditions of 142 are collected in Scheme 6.33. 1,1-Diphenylethy-lene furnished the tetracyclononene 143 in 78% yield. Styrene gave rise to a 5 1 mixture of two diastereomers 144, in the major product of which the phenyl group should occupy the trans-position relative to the bicydobutane system. The same configuration is the most probable one for 145, which resulted as a single compound (77% yield) from the trapping of 142 by 1,3-butadiene [99b]. 

Pericas and coworkers173 studied the endo selective reactions of 1-alkoxy-l,3-butadienes and 1-alkoxy-l,3-octadienes with maleic anhydride. They found that the trans-2-phenyl-cyclohexan-l-ol and 3-exo-(neopentyloxy)isobornan-l-ol based chiral dienes induced the highest facial selectivities. The relative transition state energies for the formation of the different diastereomers were calculated using semi-empirical methods (AMI). 

A complete regioselectivity has also been observed63 in chlorine addition to traits,trans-l-phenyl-4-(2,6-dichlorophenyl)-l,3-butadiene (25a) leading to the addition product (26) on the more hindered double bond (equation 32). The d.v,/ram-isomer 25b reacts similarly, although in this case the higher reactivity of the cis double bond might contribute... 

Present evidence indicates that 1-phenyl-l,3-butadiene prepared by this method is the trans isomer. ... 

HEXAHYDRO - 4a,5 - DIMETHYL - 2(3H) - NAPHTHALE-NONE and 2-TRIMETHYLSILYLOXY-1,3-BUTADIENE AS A REACTIVE DIENE DIETHYL trans -4-TRIMETHYL-SILYLOXY-4-CYCLOHEXENE-1,2-DICARBOXYLATE. Sulfur substitution also continues to be of high interest, and three preparations on sulfide synthesis are included BENZYL SULFIDE DIALKYL AND ALKYL ARYL SULFIDES NEOPENTYL PHENYL SULFIDE and UNSYMMETRICAL DIALKYL DISULFIDES sec-BUTYL ISOPROPYL DISULFIDE. 

A single chloro compound, trans-1 -phenyl-3-chloro-1 -butene (7), is formed in hydrochlorination of isomeric 1-phenyl-1,3-butadienes in AcOH135 (Scheme 6.2). The observation is interpreted by the formation of different isomeric allylic carbo-cations (6c and 6t). Rapid rotation of 6c to 6t before captured by the chloride ion ensures selective formation of 7. 

Properties of Diastereomers In contrast to enantiomeric pairs, the correpond-ing spatial distances in diastereomeric pairs are not all identical. For example, errand trans-1,2-difluoroethene (Figure 1.2.4), differ in their F-F and H-H distances. This results into different energy contents and different properties between diastereomeric molecules. The difference in properties of diastereomers is illustrated with cis- and trans-1-phenyl-1,3-butadiene, which show markedly different physicochemical properties [12] (Figure 1.2.5). Further investigation of stereochemical isomers is beyond the scope of this book, and discussion in subsequent chapters is limited to constitutional isomers. 

Figure 1.2.5 Chemical structures of cis- and trans-1-phenyl-1,3-butadiene and their normal melting point, Tm, specific gravity, df, and the refractive index, nf.

The hydrogenation of trans-l-phenyl-1,3-butadiene has been discussed49 in terms of the mechanism originally proposed,45 and 773-allyl species were invoked. NMR studies on the hydrogenation of butadiene have shown that Tj -but-2-enyl and r 3-l-methylallyl complexes are present in the reaction mixture. With isoprene, an q1 -methylbut-2-enyl complex was observed.50 By using a two-phase system and a phase-transfer catalyst, the turnover numbers attainable with conjugated dienes can be increased to about 30.51... 

Phenyl-l,2,4-triazoline-3,5-dione acts as a dienophile by in situ reaction with butadiene, cyclopentadiene, cycloheptatriene, and bicyclohepta-diene (62TL615). Thus, it is possible to compare the reactivity of the cis-azo dienophile (110) with trans-azo dienophiles, such as ethyl azodicar-boxylate, which has been observed to undergo alternate modes of reaction when used with less reactive or hindered dienes. Treatment of (110) with several dienes resulted in exclusively Diels-Alder addition. The results are summarized in Table III. 

The ethereal solution is filtered and concentrated by distillation from a steam bath to a residual volume of 80-100 ml. Some water separates at this time, and the mixture is cooled and then dried with about 15 g. of anhydrous potassium carbonate. The concentrated solution is filtered into a 125-ml. modified Claisen flask 2 and distilled under reduced pressure in a nitrogen atmosphere into a receiver containing 0.3 g. of phenyl-/j-naphthy]amine. In this manner 52-54 g. (80-83%) of crude fraws-1-phenyl-1,3-butadiene is obtained, b.p. 81—85°/10—11 mm. 1.606-1.608, which may contain some methylstyrylcarbinol and water. This material is dried with 5 g. of anhydrous potassium carbonate, filtered, and distilled as before. The yield of trans-1 -phenyl- 1,3-butadiene is 47 9 g. (72-75%), b.p. 78-81°/8 mm. 1.607-1.608. This product is satisfactory for most purposes (Notes 4 and 5). 

ANIONIC ELECTROCYCLIZA-TION USING 2,3-BIS(PHENYL-SULFONYLJ-1,3-BUTADIENE trans-4,7,7-TRICARBOMETHOXY-2-PHENYL-SULFONYLBICYCLO[3.3 0]OCT-1 -ENE... 

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