2- Methyl-3-phenyl-2-butene

The rate enhancement due to pH control was most significant with tetrasub-stituted alkenes (Table 4), making it possible to run the dihydroxylation of 2-methyl-3-phenyl-2-butene even at 0°C, which led to an increased enantioselectivity compared to earlier results (see Tables 2 and 4). However, in the case of a-methylstilbene, the constantly high pH favored the formation of higher oxidation products [11],... 

PhCCH2CH20H 1 CH3 >200°C mainly 2-methyl-3-phenyl-2-butene (82%) plus some 1,1-dimethylindane (18%)... 

Bei der Hydroaluminierung von Alkinen tritt die Oligomerisierung oft bereits bei nied-rigeren Temperaturen in den Vordergrund. So erhalt man z.B. aus 3,3-Dimethyl-l-phe-nyl-butin (I) und Bis-[2-methyl-propyl]-aluminiumhydrid (1 1) bei 50° 94% d.Th. cis-3,3-Dimethyl-l-phenyl-buten-(l) (II)5 neben 6% d.Th. trans,trans-2,2,7,7-Tetramethyl-4,5-diphenyl-octadien-(3,5) (III) ... 

Benzaldehyd + l-Brom-buten-(2) 4-Hydroxy-3-methyl-4-phenyl-buten-( I) ... 

N-Diphenylmethylen- 374 N-Diphenylmethylen-O-aminocarbonyl- 612 N-[l,3-Diphenyl-propyl-(2) - 374 N-[l,3-Diphenyl-propyliden-(2)]- 374, 377, 380 N-(4-Halogen-phenyI)- 683 N-Heptyl- 375 N-Heptyl-N-acetyl- 376 N-Heptyliden- 375 N-Hcptyliden-O-acetyl- 376 0-(2-Hydroxy-athyl)-N-athoxycarbonyl- 133 N-(4-Hydroxy-phenyl)- 683 0-(2-Hydroxy-l-phenyl-athyI)-N-athoxycarbonyI-aus 0-(ci-AthoxycarbonyI-benzyl)-N-athoxycar-bonyl-hydroxylamin und Lithiumalanat 133 N-Isopropyl- 682 N-Isopropylidcn- 613 N-Methyl- 133, 682 O-Methyl-N-bcnzyliden- 377 O-Methyl-N-benzyliden- 375 0-Methyl-N-(4-chlor-benzyl)- 375 0-Methyl-N-(4-chlor-benzyliden)- 375 N-Methy -N,0-diacetyI- 682 N-(4-Methyl-phenyl)- 683 0-McthyI-N-( 1 -phenyl-athyliden)- 375 N-(4-Methylthio-phenyl)- 684 N-(4-Nitro-benzyl)- 374 N-[4-Nitro-benzyliden - 374, 377 N-(2-Nitro-phenyl)- 562 N-(4-Nitro-phenyl)- 682 N-Nitroso-N-cyclohexyl- 697 N-Octyl- 374 N-Octyl-(2)-N-acetyl- 376 N-Octyliden- 374 N-0ctyliden-(2)-0-acctyl- 376 N-(Pentafluor-phenyl)-0,N-diacetyl- 697 N-Phenyl- 474, 481, 682, 783 N-Phenylacetyl-O-benzoyl- 265 N-(l-Phenyl-athyl)- 374 N-(l-Phenyl-athyl)-N-acetyl- 376 N-(l-Phenyl-athyliden)-374, 613 N-( l-Phenyl-athyliden)-0-acetyl- 376 N-[ 1 -Phenyl-buten-( 1 )-yl-(3)-iden]- 582 N-f4-Phenyl-butyl-(2)-iden]- 581 N-Phcnyl-N,0-diacetyl- 682 N-(4-Phenylthio-phenyl)- 684 N-Propyl-N-cyclohexyl- 376 N-Propyl-N-isopropyl- 376 O-Sulfonyl- 481 N-(4-Sulfonyl-phenyI)- 683 N-(2-Vinyl-phenyl)- 698... 

Photolysis of methyl-phenyl-diazomethane in cis-butene gives mainly styrene formed by hydride shift and the isomeric cycloaddition products 60—62 139) ... 

A similar system, (CH3)2C=CH X, was studied by Endrysova and Kraus (55) in the gas phase in order to eliminate the possible leveling influence of a solvent. The rate data were separated in the contribution of the rate constant and of the adsorption coefficient, but both parameters showed no influence of the X substituents (series 61). A definitive answer to the problem has been published by Kieboom and van Bekum (59), who measured the hydrogenation rate of substituted 2-phenyl-3-methyl-2-butenes and substituted 3,4-dihydro-1,2-dimethylnaphtalenes on palladium in basic, neutral, and acidic media (series 62 and 63). These compounds enabled them to correlate the rate data by means of the Hammett equation and thus eliminate the troublesome steric effects. Using a series of substituents with large differences in polarity, they found relatively small electronic effects on both the rate constant and adsorption coefficient. 

Table 17) with two substituents in position C3 the oxygen transfer by the chiral hydroperoxides occurred from the same enantioface of the double bond, while epoxidation of the (ii)-phenyl-substituted substrates 142c,g,i resulted in the formation of the opposite epoxide enantiomer in excess. In 2000 Hamann and coworkers reported a new saturated protected carbohydrate hydroperoxide 69b , which showed high asymmetric induction in the vanadium-catalyzed epoxidation reaction of 3-methyl-2-buten-l-ol. The ee of 90% obtained was a milestone in the field of stereoselective oxygen transfer with optically active hydroperoxides. Unfortunately, the tertiary allylic alcohol 2-methyl-3-buten-2-ol was epoxidized with low enantioselectivity (ee 18%) with the same catalytic system . 

SCHEME 44. Intermolecular kinetic isotope effect in the intrazeolite photooxygenation of 1-phenyl-3 -methyl- 2-butene... 

Additionally, in order to elucidate the energy reaction profile in the intrazeolite photooxygenation of trisubstituted alkenes, the competing photooxygenation of l-phenyl-3-methyl-2-butene and its geminal methyl deuteriated analogues (Scheme 44) was studied . ... 

TABLE 18. Cation-dependent regiochemical control in the intra i t tooxygenation of 1- phenyl-3-methyl-2-butene e p o-... 

Phenyl hydroperoxide, C-O distance, 103 (y-Phenylhydroperoxides, nucleophiUc substitution cyclization, 234-5 1 -Phenyl-3-methyl-3-butene, intrazeohte photooxygenation, 874-5 Phenyl substituted alkenes, photooxidation site selectivity, 839-42... 

N-(phenyl methylene)- (622-29-7), 65, 140 2-Methyl-2-butene 2-Butene, 2-methyl- (513-35-9), 65, 159 Methyl carbamate Carbamlc acid, methyl ester (598-55-0), 65, 159 METHYL 4-CHLORO-2-BUTYNOATE 2-BUTYN0IC ACID, 4-CHL0R0-, METHYL ESTER (41658-12-2), 65, 47... 

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. 

H and 13C KIEs were determined for the ene reaction of 4-phenyl-l,2,4-triazoline-2,5-dione (PTAD) with 2-methyl-2-butene 44 or 2-methyl-l-pentene 45 (Scheme 7).91 Authors assumed that although in the reaction of 2-methyl-l-pentene two products are formed, reactions should proceed via very similar transition states in the first mechanistic step. 

The indium-mediated aqueous Barbier-type reaction of crotyl bromide with benzaldehyde shows no diastereo-selectivity. However, the use of preformed crotylindium sesquibromide in DMF affords. sy/z-l-phenyl-2-methyl-3-buten-l-ol (ca. 40% de) after aqueous acidic workup. At 22 °G in DMF prior to workup, a greater relative proportion of //-intermediate is decomposed as compared to its yy/z-diastereomer. The resultant kinetic diastereoselection upgrades the syn anti ratio to 99 1 with a concomitant drop in overall yield (Scheme 14).127... 

R2Te2 + NaBH4/C2Hs0H ch3 1 H3C C = CH-CH2 Br 3-methyl-2-buten-l-yl phenyl tellurium - - - - 2... 

The silicon-carbon double-bonded intermediates generated photo-chemically from a-alkenyldisilane derivatives react with both enolizable and nonenolizable ketones to give olefins (98). For instance, the photolysis of a-styrylpentamethyldisilane (49) in the presence of one molar equivalent of acetone gives l-trimethylsilyl-2-phenyl-3-methyl-2-butene in 13% yield as a single product. No silyl enol ether to be expected from the reaction of the intermediate with the enol form of acetone is observed. Similar irradiation of 49 with acetophenone affords (E)- and (Z)-l-trimeth-... 

Buten 3-Hydroximino-2-methyl-l-(4-methyl-phenyl)-E14b, 315 (aus En — on)... 

Phosphinsaure (l-Diazo-3-methyl-2-buten-2-yl)-phenyl- -methylester E14b, 1331 (aus Hydrazon)... 

Catalytic hydrosilylation of alkenes performed in the presence of a chiral catalyst results in the formation of chiral silanes. Initially platinium catalysts of the type L PtCl2, L = (/ )-benzyl-(methyl)phenylphosphine (BMPP) or (/ )-methyl(phenyl)propylphosphine and 1,1-disubstituted prostereogenic alkenes, such as a-methylstyrene, 2,3-dimethyl-l-butene and 2-methyl-l-butene, were used however, the stereoselectivity was low4,5. A slightly higher stereoselectivity is obtained when dichlorobis[(/ )-benzyl(methyl)phenylphosphine]nickel [Ni(BMPP)2Cl2] is used as the catalyst. Note that two chiral silanes are formed in this reaction, both of which are products of anti-Markovnikov addition. The major product is the expected dichlorosilane 3, while the byproduct is an anomalous chlorosilane 4 both products were separated by fractional distillation and the major product methylated to give the trimethylsilanes 56 7. 

A similar example is seen in the [Pd2(dba)3]-catalyzed hydroboration of 2-methyl-l-buten-3-ynes [274]. While PPhj and PPh2(CgF5) favor the 1,4-addition product allenylborane 100 all diphosphines yield the 1,2-addition product ( )-dienylborane 102 exclusively (Table 1-13). This remarkable difference in selectivity is explained based on an 1,3-enyne monophosphine complex 103 and an alkynyl diphosphine complex 104 as intermediates. Dppf exhibits the best product yield among the phosphines tested. Similar observation was noted in the asymmetric hydroboration (Scheme 1-44) [275]. The action of catecholborane on 1-phenyl-1,3-butadiene also proceeds regioselectively to give, after oxidation, anti-l-phenyl-l,3-butanediol... 

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