1-phenyl-1-alkenes

Zimtaldehyd und 3-Oxo-1-phenyl-1-alkene liefern ebenfalls Hydrodimere z. B. ... 

Auch l-(2-Nitro-phenyl)-alkene geben in 0,5n-athanol. Schwefelsaure 4-Amino-3-[alken-( 1 )-yl]-pheno e (zur Indol-Synthese)4. Auch 5-Nitro-isochinolin kann so zu 5-Amino-8-hydroxy-isochinolin reduziert werden5. Analog erhalt man aus 4-Nitro-ben-zotriazol an Platin/konzentrierter Schwefelsaure 4-Amino-7-hydroxy-benzoiriazoP. 

Ordinary alkenes are usually unaffected by Birch-reduction conditions, and double bonds may be present in the molecule if they are not conjugated with the ring. However, phenylated alkenes, internal alkynes (p. 1009), and conjugated alkenes (with C=C or C=0) are reduced under these conditions. 

Alkenes formed bis trifluoroacetates of glycols in their reaction with BTI with phenylated alkenes rearranged products dominated, e.g. tetraphenylethylene was... 

Simple alkenes do not give with (difluoroiodo)arenes clean reactions phenylated alkenes under ionic conditions undergo addition of fluorine accompanied by rearrangement in presence of acid (HF, CF3COOH). The reaction proceeds through an initial fluoroalkyl phenyliodonium adduct which is transformed to a phenonium cation and eventually to the rearranged product ... 

Lubczyk H, Bachmann R, Gust R (2003) Antiestrogenically active 1, 1, 2-tris(4-hydroxy-phenyl)alkenes without basic side chain synthesis and biological activity. J Med Chem 46 1484-1491... 

The reaction of an aryl diazonium halide with an aliphatic unsaturated compound to yield an a-halo-P-phenyl alkene and alkanes. The reaction is performed in the presence of cupric ious. The presence of an electron-withdrawing group is useful in promoting the reactivity of the alkene. See Kochi, J.K., The Meerwein reaction. Catalysis by cuprous chloride, J. Am. Chem. Soc. 11, 5090, 1955 Morales, L.A. and Eberlin, M.N., The gas-phase Meerwein reaction, Chemistry 6, 897-905, 2000 Riter, L.S., Meurer, E.C., Handberg, E.S. et al, lon/molecule reactions performed in a miniature cylindrical ion trap mass spectrometer. Analyst 128, 1112-1118, 2003 Meurer, E.C., Chen, H., Riter, E.S. et al., Meerwein reaction of phosphonium ions with epoxides and thioepoxides in the gas phase, J. Am. Soc. Mass Spectrom. 15, 398 05, 2004 Meurer, E.C. and Eberlin, M.N., The atmospheric pressure Meerwein reaction, J. Mass Spectrom. 41, 470-476, 2006. 

In the absence of other factors, therefore, the adsorption energies of a group of isomeric conjugated polyenes or phenyl alkenes should increase as the number of Irons double bonds increases or the number of cis double bonds decreases. Jacques and Kagan 41) have summarized the relative adsorption affinities of several compounds of this type ... 

Bowman s approach to imidoyl radicals commenced with imidoyl selanides [48, 49], Subsequent cyclization onto electron-deficient a,p-unsaturated esters (Z = C02Et) as well as to electron-rich propyl- and phenyl-alkenes (Z = Pr, Ph) gave 2,3-disubstituted indoles in moderate to excellent yields with no evidence of the products of simple reduction. 

Table 5.11. Transition Temperatures of Poly(phenyl alkenes)... 

When benzene is a substituent in a molecule, it is called phenyl. Alkenes and functional groups are important in biological systems. 

Alkenes in (alkene)dicarbonyl(T -cyclopentadienyl)iron(l+) cations react with carbon nucleophiles to form new C —C bonds (M. Rosenblum, 1974 A.J. Pearson, 1987). Tricarbon-yi(ri -cycIohexadienyI)iron(l-h) cations, prepared from the T] -l,3-cyclohexadiene complexes by hydride abstraction with tritylium cations, react similarly to give 5-substituted 1,3-cyclo-hexadienes, and neutral tricarbonyl(n -l,3-cyciohexadiene)iron complexes can be coupled with olefins by hydrogen transfer at > 140°C. These reactions proceed regio- and stereospecifically in the successive cyanide addition and spirocyclization at an optically pure N-allyl-N-phenyl-1,3-cyclohexadiene-l-carboxamide iron complex (A.J. Pearson, 1989). 

The isoflavone 406 is prepared by the indirect a-phenylation of a ketone by reaction of phenylmercury(II) chloride with the enol acetate 405, prepared from 4-chromanone[371]. A simple synthesis of pterocarpin (409) has been achieved based on the oxypalladation of the oriho-mercurated phenol derivative 408 with the cyclic alkene 407[372,373]. 

Many examples of insertions of internal alkynes are known. Internal alkynes react with aryl halides in the presence of formate to afford the trisubstituted alkenes[271,272]. In the reaction of the terminal alkyne 388 with two molecules of iodobenzene. the first step is the formation of the phenylacetylene 389. Then the internal alkyne bond, thus produced, inserts into the phenyl-Pd bond to give 390. Finally, hydrogenolysis with formic acid yields the trisubstituted alkene 391(273,274], This sequence of reactions is a good preparative method for trisubstituted alkenes from terminal alkynes. 

Pyrazoles are formed when the diazo compounds react with alkynes or with functionalized alkenes, viz. the enols of /3-diketones. Pyrazolenines (353 Section 4.04.2.2.1) are isolated from disubstituted diazomethanes. Many pyrazoles, difficult to obtain by other methods, have been prepared by this procedure, for example 3-cyanopyrazole (616) is obtained from cyanoacetylene and diazomethane (7iJCS(C)2i47), 3,4,5-tris(trifiuoromethyl)pyrazole (617) from trifluorodiazoethane and hexafluoro-2-butyne (8lAHC(28)l), and 4-phenyl-3-triflylpyrazole (618 R =H) from phenyltriflylacetylene and diazomethane (82MI40402). An excess of diazomethane causes iV-methylation of the pyrazole (618 R = H) and the two isomers (618 R = Me) and (619) are formed in a ratio of 1 1. 

When compound (443), which contains alkene and alkyne moieties, was reacted with benzonitrile oxide, both an isoxazoline (444) and isoxazole (445) were produced, with the former predominating. Oxidation of (444) with permanganate produced 3-phenyl-2-isoxazoline-5-carboxylic acid (446) (67ZOR82i). The reaction of 1-trimethylsilylbut-l-yne-3-ene produced only a compound which reacted at the alkenic unit. Oxidation of the adduct also produced (446) (68ZOB1820). These reactions are shown in Scheme 102. 

Nitrones or aci-nitro esters react with alkenes to give in some cases A/-substituted isoxazolidines and in others 2-isoxazolines. When the intermediate isoxazolidines were observed, a number of procedures transformed them into the 2-isoxazolines. Acrylonitrile and phenyl rzcf-nitrone esters produced an A/-methoxyisoxazolidine. Treatment with acid generated a 2-isoxazole while treatment with base generated an oxazine (Scheme 118) (68ZOR236). When an ethoxycarbonyl nitrone ester was reacted with alkenes, no intermediate isoxazolidine was observed, only A -isoxazolines. Other aci-mtro methyl esters used are shown in Scheme 118 and these generate IV-methoxyisoxazolidines or A -isoxazolines which can be further transformed (72MI41605). 

Heating or irradiating alkenes in the presence of sulfur gives relatively low yields of thiiranes. For example, a mixture of sulfur and norbornadiene in pyridine-DMF-NHa at 110 °C gave a 19% yield of the monoepisulfide of norbornadiene as compared with a 78% yield by the method of Scheme 120 (79JCS(Pi)228). Often 1,2,3-trithiolanes are formed instead of thiiranes. The sesquiterpene episulfides in the essential oil of hops were prepared conveniently by irradiation of the terpene and sulfur in cyclohexane (Scheme 135) (80JCS(Pl)3li). Phenyl, methyl or allyl isothiocyanate may be used as a source of sulfur atoms instead of elemental sulfur. 

The mechanism of the reaction is unknown. The stereospecificity observed with (E)- and (Z)-l-methyl-2-phenylethylene points to a one-step reaction. The very low Hammett constant, -0.43, determined with phenylethylenes substituted in the benzene ring, excludes polar intermediates. Yields of only a few percent are obtained in the reaction of aliphatic alkenes with (52). In the reaction of cyclohexene with (52), further amination of the aziridine to aminoaziridine (99) is observed. Instead of diphenylazirine, diphenylacetonitrile (100) is formed from diphenylacetylene by NH uptake from (52) and phenyl migration. 

Other isocyanates undergo [2 + 2] cycloaddition, but only with very electron rich alkenes. Thus phenyl isocyanate gives /3-lactams with ketene acetals and tetramethoxyethylene. With enamines, unstable /3-lactams are formed if the enamine has a /3-H atom, ring opened amides are produced 2 1 adducts are also found. Photochemical addition of cis- and traH5-stilbene to phenyl isocyanate has also been reported (72CC362). 

A significant modification in the stereochemistry is observed when the double bond is conjugated with a group that can stabilize a carbocation intermediate. Most of the specific cases involve an aryl substituent. Examples of alkenes that give primarily syn addition are Z- and -l-phenylpropene, Z- and - -<-butylstyrene, l-phenyl-4-/-butylcyclohex-ene, and indene. The mechanism proposed for these additions features an ion pair as the key intermediate. Because of the greater stability of the carbocations in these molecules, concerted attack by halide ion is not required for complete carbon-hydrogen bond formation. If the ion pair formed by alkene protonation collapses to product faster than reorientation takes place, the result will be syn addition, since the proton and halide ion are initially on the same side of the molecule. 

Alkenes lacking phenyl substituents appear to react by a similar mechanism. Both the observation of general acid catalysis and the kinetic evidence of a solvent isotope effect are consistent with rate-limiting protonation with simple alkenes such as 2-metlQ lpropene and 2,3-dimethyl-2-butene. 

Part B of Table 12.2 gives some addition reaction rates. Comparison of entries 19 and 20 shows that the phenyl radical is much more reactive toward addition than the benzy 1 radical. Comparison of entries 22 and 23 shows that methyl radicals are less reactive than phenyl radicals in additions to an aromatic ring. Note that additions to aromatic rings are much slower than additions to alkenes. 

This addition to the aromatic ring is believed to be eoncerted, since the relative geometry of the substituents on the alkene is retained in the product. Lesser amounts of products involving addition to 1,2- or 1,4-positions of the aromatic ring are also formed in such photolyses. ° This type of addition reaction has also been realized intramolecularly when the distance between the alkene and the phenyl substituent is sufficient to permit interaction. 

Vinyl Inflates permit alkylation with vinyl cations [24, 25] Fluorobenzene reacts with 2 methyl 1-phenyl 1 propenyl triflate to form a diaryl alkene [24J (equation 17)... 

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