Phenyl-4-bromo-2-butene

Ketones such as methyl cyclohexyl ketone 1284 react with DMSO/TCS 14, via their enol form, to give 21% of the chloroketone 1285 a and 63% of the a-methyl mercaptoketone 1286 [70]. Reaction of 1284 with DMSO/MesSiBr (TBS) 16 affords 85% of the bromo compound 1285 b and 12% hexahydrophenacyl bromide 1287 but no 1286 [71]. Whereas reaction of tra s-4-phenyl-3-buten-2-one (benzalacetone) 1288 with DMSO/TCS 14 gives 81% of the sulfonium salt 1289 [70], the y9-dicar-bonyl compound ethyl acetoacetate furnishes 69% of 1290 [70]. In contrast with DMSO/TCS 14, the combination DMSO/TBS 16 effects selective monobromina-tion of y9-dicarbonyl compounds [71] (Scheme 8.28). 

Trigonally hybridized vinyllithium derivatives are characterized by higher configurational stability [34,35]. Panek [36] demonstrated that (E) and (Z)-l-lithium-l-phenyl-l-butene could be prepared stereospecifically, with retention of configuration, by a lithium-halogen exchange reaction between n-butyllithium and (Z) and ( )-l-bromo-l-phenyl-1-butene, respectively (Scheme 7). Both lithium derivatives are configurationally stable at... 

S,3Sj-2-Bromo-3-phenylbutane undergoes an E2 reaction when treated with a strong base to produce (E)-2-phenyl-2-butene. Use Newman projections to explain the stereochemical outcome of this reaction. 

These results are in accordance with the findings of Boothe and coworkers26, who found that the reactions of four diastereomeric 2-bromo-3-phenylsulfinylbutanes with tributyl-tin radicals generate /3-phenylsulfinyl sec-butyl radicals (8) which eliminate PhSO radicals to form the 2-butenes in a stereoselective manner. The stereoselectivities observed in this free radical elimination must result from the fact that the rate constant for elimination is greater than that for rotation about the C—C bond. Furthermore, a neighboring phenyl group on the radical center seems to stabilize the radical enough so that the internal rotation can compete with the -elimination reaction. It is also noteworthy that the small... 

Tatsuo Ishiyama, Norio Miyaura, and Akira Suzuki 89 PALLADIUM(0)-CATALYZED REACTION OF 9-ALKYL-9-BORABICYCLOJ3.3.1]-NONANE WITH 1 -BROMO-1 -PHENYL-THIOETHENE 4-(3-CYCLOHEXENYL)-2-PHENYLTHIO-1-BUTENE... 

The addition of HBr to 2-methyl-l,3-pentadiene, 1-bromo-1,3-butadiene, 1-phenyl-1,3-butadiene and 2,4-hexadiene produces 2,4-dibromo-2-methylpentane, 1,3-dibromo-l-butene, 3-bromo-l-phenyl-1-... 

A mixture of 14.91 g (135.324 mmol) of thiophenol and 5.5 g (137.5 mmol) of NaOH in 100 ml acetone was heated at reflux for 2.5 h and then treated dropwise with a solution of 20 g (134.19 mmol) of l-bromo-3-methyl-2-butene in 20 ml acetone. This solution was refluxed for 40 h and then stirred at room temperature for 24 h. Solvent was then removed in vacuo, the residue taken up in water, and extracted with 3 times 50 ml ether. Ether extracts were combined and washed with 3 times 30 ml of 5% NaOH solution, then water, saturated NaCI solution and dried. Solvent was then removed in vacuo and the residue further purified by kugelrohr distillation (80°C, 0.75 mm) to give the phenyl-3-methylbut-2-enylsulfide as a pale yellow oil. 

Phenyl-2-bromobutene-r, 6, 27 Phenyl-4-bromo 2-butene-i, 6, 2.1 iV-Phenyl carbazole, 8,119 Phenyl ethylene, 8, 84 Phenylhydhazine, 2, 71 /3-Phenyl Hydroxylamine, 4, 19, ff... 

The anti addition of diethyl 7V,Ar-dibromophosphoramidates to acyclic and cyclic alkenes was achieved in the presence of boron trifluoride, which makes the ionic dissociation of the N —Br bond more labile94,9s. After reduction of the initial /J,lV-dibromo adducts with sodium bisulfite, the /i-bromo-A -hydrophosphoramides 3 precursor of / -bromo amine hydrochlorides 4 were obtained (Table 4). However, a mixture of diastereomers was obtained from (Z)-l-phenyl-l-propene and (E)- and (Z)-l,2-diphenylethylene. Direct assignment of stereochemistry by H NMR of the phosphoroamidates derived from 2-butenes was not possible. Detailed analysis is, however, possible for the H-NMR spectra of the /J-bromo amine hydrochlorides. As determined by 31P NMR spectroscopy all additions to unsymmetrical aliphatic alkenes were not regiospecific. The /f-bromo amine hydrochlorides were converted to 1,2-diamines95. 

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