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PHENYL-l,3-BUTADIENE

Geminal dibromocyclopropanes have been reduced by chromium(lI) - (-i-)-tartrate complex and by butyllithium - (+)-sparteine complex to give cyclic allenes and 1-phenyl-l,2-butadiene with very low enantioselectivity (< 1 % op)122. In addition, cyclic diallenes of unknown optical purity have been reported123, l24, e.g., 3,4,9,10-cyclododecatetraene-l,7-dione is prepared using a stoichiometric amount of methyllithium and a sixfold excess of (-)-sparteine123,124. [Pg.561]

The allenes, RC=C=CR, are readily prepared by this method from tetrahalides and dihalo olefins. Typical procedures are given for methyl-allene (72%) and 1-phenyl-l,2-butadiene (77%). A convenient route to the allenes from allyl halides is as follows ... [Pg.25]

The reaction for unsymmetrically 1,3-disubstituted allenes was highly diastereos-elective butnotregioselective. Addition of 1 equiv of racemic 1-phenyl-l,2-butadiene to a solution of ( )-97 produced exclusively the regioisomers 99 and 100. [Pg.44]

Zhang and Widenhoefer have reported a highly regio- anddiastereo-selective method for the intermolecular hydroalkoxylation of aUenes with alcohols [108]. As an example, reaction of 1-phenyl-l,2-butadiene with 2-phenyl-l-ethanol catalyzed by a 1.1 mixture of (IPr)AuCl [IPr = l,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene] and AgOTf in toluene at room temperature led to isolation of ( )-(3-phenethoxy-l-butenyl)benzene in 96% yield as a single regio- and stereo-isomer (Eq. (12.38)). The protocol was effective for primary and secondary alcohols and for monosubstituted, 1,1- and 1,3-disubstituted, trisubstituted, and tetrasubstituted allenes. Transfer of moiety to the newly formed tetrahedral stereocenter in the y o oxy ation of axially chiral 1,3-disubstituted allenes ranged from 0 to 81%, epen ing on the nature of the allene and the concentration of the alcohol. [Pg.482]

Nishina and Yamamoto have also reported the gold(I)allenes with alcohols [109]. As an example, treatment of a neat mixture of p-tolyl allene and isopropanol with a catalytic 1 1 mixture of (PPh3)AuCl and AgOTf at 30 °C led to isolation of isopropyl )-3-(4-tolyl)-2-propenyl ether in 98% yield (Eq. (12.39)). The protocol was most effective for monosubstituted and 1,3-disubstituted allenes and gave no transfer of chirality for the hydroalkoxylation of 1-phenyl-l,2-butadiene. Horino has reported the gold(I)-catalyzed intermolecular addition of alcohols to the allenyl moiety of 4-vinylidene-2-oxazolidinones [110]. [Pg.483]

Section II, 1. Theoretical aspects of asymmetric polymerization have been discussed by Fueno and Furdkawa [T. Fueno, J. Furukawa J. Polymer Sci., Part A, 2, 3681 (1964)]. 1-phenyl-l,3-butadiene has been polymerized using (R)-2-methyl-butyl-lithium or butyl-lithium complexed with menthyl-ethyl-ether, yielding optically active polymers with [a] f, referred to one monomeric unit, between +0.71 and —1.79. Optical rotation dispersion between 589 m u and 365 mft is normal and the Drude equation constant is comprised between 255 raft and 280 raft [A. D. Aliev, B. A. Krenisel, T. N. Fedoiova Vysokomol. Soed. 7, 1442 (1965)]. [Pg.455]

This preparation is based on a procedure published by the submitters.8, 9 9-Phenylphenanthrene has been prepared previously by the reaction of phenyllithium with 9-chlorophehanthrene,10 by the high-temperature dehydrogenation with palladium on charcoal of the Diels-Alder dimer of 1-phenyl-l,3-butadiene,11 and by the acid-catalyzed cyclization of the alcohol formed from the reaction of 2-biphenylylmagnesium iodide and 2-phenoxy-acetophenone.3... [Pg.94]

The asymmetric hydrocyanation of dienes with substantial enantioselectivities has also been reported (Equation 16.10). Like the reactions of vinylarenes, these reactions have been reported with catalysts containing carbohydrate-derived phosphinites. Reactions of aryl-substituted dienes occur to form the products from 1,2-hydrocyanation. In addition to the reactions of purely acyclic dienes, such as 1-phenyl-l,3-butadiene, dienes containing an exocyclic vinyl group have been studied. These are substrates for products possessing... [Pg.675]

Determine which diene, (a) or (b), will react fastest with maleic anhydride (LUMO = -0.57 eV) (a) 1-phenyl-l,3-butadiene (HOMO = -8.16 eV) or (b) penta-2,4-dienoic acid (HOMO = -9.41 eV). [Pg.1249]

The addition of a hydrogen halide (hydrogen bromide or hydrogen chloride) to 1-phenyl-l,3-butadiene produces (only) l-phenyl-3-halo-l-butene. (a) Write a mechanism that accounts for the formation of this product, (b) Is this 1,4 addition or 1,2 addition to the butadiene system (c) Is the product of the reaction consistent with the formation of the most stable intermediate carbocation (d) Does the reaction appear to be under kinetic control or equilibrium control Explain. [Pg.722]

Using 4 mol % of Pd(dba)2 plus 4 mol % of a chiral phosphine ligand such as BINAP, DIOP, MOD-DIOP, and ferrocenyl phosphines, the reaction of Phi, ( )-l-phenyl-l,2-butadiene, and sodium dimethyl malonate afforded chiral nomacanic (5)-dimethyl 1-methyl-2,3-diphenylallyl malonate 69 with up to 96% ee (Scheme 26)4 i... [Pg.1502]

Asymmetric hydroboration of 1-phenyl-l,3-butadiene (95) catalyzed by Rh-BINAP gave the corresponding optically active 1,3-diol 155 with 72% ee (89,90] (Schrane 2.15). Palladium-MOP complex also exhibited catalytic activity for the asymmetric hydroboration of but-l-en-3-yne (156), giving an optically active allenyl borane 157 [91]. [Pg.136]

A further extension of the MIMIRC reaction is seen in the synthesis of enantiomerically pure cyclohexanones. A successful diastereoselective MIMIRC reaction with 2-(rer/-butyldimethylsi-lyloxy)-4-phenyl-l,3-butadiene and an optically pure (Z)-y-alkoxy-substituted enone was performed using catalytic amounts (5 mol%) of triphenylmethyl perchlorate at — 78 ,C 360,408 (for a further example see Section 1.5.2.4.4.1.). [Pg.998]

The amination of styrene, however, led to two products (1-phenyl-1-ethylamine and 2-phenyl-l-ethylamine) in a 1 3 ratio [113], indicating that the hydrozirconation was not completely regioselective [114,115]. Since it is well known that hydrozirconation of trisubsti-tuted alkenes places zirconium at the least hindered carbon of the chain by a process involving zirconium migration, this class of alkenes was not investigated [5,116], On the other hand, hydrozirconation/amination of 3-methyl-l,2-butadiene gave an allylic amine. Reaction of the latter could either occur at the terminal carbon or proceed with... [Pg.247]

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). [Pg.391]

The (diphenylmethylene)aminocyclobutenecarboxylates 109 obtained by rearrangement of the DMPA-H adducts of 1-Me, 2-Me, contain a 2-azadiene unit and a cyclobutene moiety. Indeed, the parent compound 109 a reacted with 4-phenyl-l,2,4-triazoline-3,5-dione (PTAD, [80]) at room temperature in a [4-1-2] cycloaddition mode to yield the tricyclic tetraazaundecene 132 in almost quantitative yield (Scheme 44) [8]. As substituted cyclobutenes, compounds 109 should be capable of opening up to the corresponding butadienes [1, 2b, 811. When compounds 109 were subjected to flash vacuum pyrolysis, the dihydro-isoquinolines 135 were obtained, presumably via the expected ring-opened intermediates 133, which subsequently underwent bn electrocyclization followed by a 1,5-shift, as is common for other 3-aza-l,3,5-hexatrienes [82]. [Pg.188]

E. [l,4-BIS(METHOXYCARBONYL)-2-METHYL-3-PHENYL-l,3-BUTADIENE-1,4-DIYL]-(ti5-CYCLOPENTADIENYL)-(TRIPHENYLPHOSPHINE) COBALT AND [1,3-BIS(METHOX YCARBONYL)-2-METH YL-4-PHENYL-1,3-BUT ADIENE-1,4-DI YL]-(q 5-C Y CLOPENT ADIENYL)-(TRIPHENYLPHOSPHINE)COBALTt... [Pg.197]

Bis(methoxycarbonyl)-2-methyl-3-phenyl-l, 3-butadiene-1,4-diyl]cobalt=2,5-dicarbo-methoxy-3-phenyl-4-methylcobaltacyclopentadiene. [Pg.197]

CoClPjC H, Cobalt, chlorotris-(triphenylphosphine)-, 26 190 CoN203C15H9, Cobalt, tricarbonyl[2-(phenylazo)phenyl-C, A ]-, 26 176 CoO PC3jHm, Cobalt, (V 2-propynoate) (triphenylphosphine)-, 26 192 CoC PCmH, Cobalt, (Ty -cyclopentadienyl) [ 1,3-bis(methoxycarbonyl)-2-methyl-4-phenyl-l, 3-butadiene-1,4-diyl]-(triphenylphosphine)-, 26 197... [Pg.417]

Conjugation in the form of a phenyl substituent at the 2-position leads to 8-10 ppm deshielding of the fluorines of a terminal vinylic CF2 group, whereas for a conjugating vinyl group at the 2-position (as in 1,1-difluoro-l,3-butadiene) such deshielding is somewhat less... [Pg.172]

Butadienes with alkyl substituents in the 2-position favor the formation of the so-called para products (Figure 12.24, X = H) in their reactions with acceptor-substituted dienophiles. The so-called meta product is formed in smaller amounts. This orientation selectivity increases if the dienophile carries two geminal acceptors (Figure 12.24, X = CN). 2-Phenyl-l,3-butadiene exhibits a higher para selectivity... [Pg.497]


See other pages where PHENYL-l,3-BUTADIENE is mentioned: [Pg.721]    [Pg.79]    [Pg.499]    [Pg.40]    [Pg.139]    [Pg.1756]    [Pg.78]    [Pg.131]    [Pg.528]    [Pg.1756]    [Pg.3]    [Pg.146]    [Pg.170]    [Pg.127]    [Pg.254]    [Pg.216]    [Pg.137]    [Pg.16]    [Pg.12]    [Pg.604]    [Pg.435]   
See also in sourсe #XX -- [ Pg.47 , Pg.59 ]

See also in sourсe #XX -- [ Pg.47 , Pg.59 ]




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1 Phenyl 1,3 butadiene

L -Butadien

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