Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Methyl phenylpropiolate

In 1973 two papers appeared almost simultaneously (73T101, 73CPB2026) describing the formation, as a minor product, of 3,4,5-trimethoxycarbonyl-l-phenylpyrazole (346) in the reaction between benzaldehyde phenylhydrazone and DMAD (EC=CE). To account for the formation of (346) George et al. (73T101) proposed a tentative mechanism (Scheme 29) involving a Diels-Alder reaction of type (a Figure 25), followed by a retro-Diels-Alder elimination of methyl phenylpropiolate (347). [Pg.248]

Similarly, methyl propiolate and methyl phenylpropiolate give the cyclazine (67) and its 2-phenyl derivative, respectively, as would be expected of reactions initiated through a Michael addition to the acetylenic ester. [Pg.141]

The cross-dimerization of various electron-rich 1-alkynes 5 with electron-deficient internal alkynes such as methyl phenylpropiolate 6 was promoted by an [lrCl(cod)]2 combined with bidentate phosphine ligands such as (racj-BlNAP (Equation 10.2) [16]. This reaction produces a 1 1 adduct 7 in high regioselectivity and stereoselectivity. [Pg.252]

The reaction of indolizines with dialkyl acetylenedicarboxylates in the presence of a dehydrogenating catalyst leads to 1,2-dicarbalkoxycycl-[3,2,2]azines.22 23 Methyl phenylpropiolate may be used instead, although attempts to effect reaction between indolizine and certain other dienophiles including diphenylacetylene, diethyl azodicarboxylate, and 1,3-cyclohexadiene were unsuccessful. Hydrolysis of the diesters yielded the corresponding acids. Subsequent decarboxylation proceeded in high yield using copper chromite in quinoline [Eq. (5)]. [Pg.328]

Similarly, cyclization of 3-amino-l, 2,4-triazoles (65) with methyl propio-late or methyl phenylpropiolate gave a mixture of the l,2,4-triazolo[4,3-a]pyrimidin-7-ones 97 and the l,2,4-triazolo[l,5-a]pyrimidin-7-ones 98 (70CB3266 71CB2702). In addition, methyl tram-3-(3-amino-l,2,4-triazol-l-yl)acrylates (99) were also obtained. Production of the 1,2,4-triazolopy-rimidines 97 and 98 started by condensation of the ester function with the amino group of 65, followed by cycloaddition of the triazole N4 or N1 of the two tautomeric intermediates 96a and 96b, respectively, onto the carbon-carbon triple bond of the side chain. In contrast, formation of the triazolyl acrylates 99 took place through addition only of the triazole N1 onto the propiolate carbon-carbon triple bond. The relative amounts of products were found to depend on the reaction conditions (temperature, solvent, and time) (70CB3266) (Scheme 42). [Pg.154]

Cyclazines (76) were obtained from the reaction of indolizines with DMAD or methyl phenylpropiolate in the presence of a dehydrogenating catalyst (Scheme 8) (78AHC(22)32l). Theoretical considerations concerning the mechanism of the reaction have been presented (61JA453) which has been assumed to be of a concerted [W8S + 2S] type on the basis of resonance energy differences between the pericyclic transition state and the reactants (78BCJ1788). [Pg.459]

Bis-amine disulfides can serve as sulfur sources in a radical condensation with two equivalents of an alkyne. When a mixture of a bis-amine disulfide and phenylacetylene was heated in a Paar bomb for three hours at 140 °C, an 82% yield of a mixture of 2,5-diphenylthiophene (278 R1 = Ph, R2 = H) and 2,4-diphenylthiophene (279) was obtained. 2,4-Diphenylthiophene was the major product, constituting 85% of the mixture. When methyl propiolate was so treated, the only product was (278 R1 = C02Me, R2 = H) in about 48% yield. Similarly, methyl phenylpropiolate gave only (278 R1 = C02Me, R2 = Ph) in 67% yield. Thus there is a degree of regiospecificity to the reaction, and a radical mechanism which ultimately involves a polar [3 + 2] mechanism, as shown in Scheme 23, was proposed (77TL3413). [Pg.900]

Tinnemans and Neckers [62,63] have published a reinvestigation of the photoaddition of methyl phenylpropiolate to benzene, originally reported by Bryce-Smith et al. [60], Irradiation with a 450-W medium-pressure mercury lamp through Pyrex produces methyl 5-phenyltetracyclo[3.3.0.02,4.03,6]oct-7-ene-4-carboxylate (I) (65-70%) (Scheme 11). [Pg.14]

Scheme 11 Photochemical addition of methyl phenylpropiolate to benzene. Scheme 11 Photochemical addition of methyl phenylpropiolate to benzene.
However, through quartz at 95% conversion, a mixture of I (62%) and l-carboxymethyl-2-phenylcyclooctatetraene (IT) (38%) was obtained. Compound n could be obtained exclusively (92%) from triplet-sensitized irradiation of I with high-energy sensitizers or from the sensitized reaction of methyl phenylpropiolate with benzene. From their experiments with sensitizers, the authors concluded that the primary adduct is formed from triplet alkyne (ET < 69 kcal/mol 1) and ground-state benzene and that the formation of I also proceeds via a triplet state in a two-step radical reaction. Hanzawa and Paquette [64] have also used the photochemical addition of an alkyne to benzene to produce a derivative of tetra-cyclo[3.3.0.02,4.03 6]oct-7-ene. [Pg.15]

In this case, only a thermal pathway for the formation of the cyclooctatetraene is proposed, in agreement with many other publications (for references, see Sec. II and Table 3). Tinnemans and Neckers [62], however, describe the ring opening of the ortho adduct from methyl phenylpropiolate and benzene as well as the reverse reaction as photochemical processes. The formation of this ortho adduct can also be accomplished in a xanthone-sensitized photoreaction [63], and in that case, the authors consider the ring opening as a thermal or a triplet-sensitized reaction and the reverse reaction as one proceeding via the singlet. [Pg.110]

Several acetylenic esters have been shown to react with phenan-thridine-5-oxide (or its 6-alkyl derivatives) forming adducts of the type (21 5).308 Under necessarily more vigorous conditions (in di-methylformamide at 100°) the less reactive methyl phenylpropiolate combined with 6-methylphenanthridine-5-oxide to form 2-phenyl-pyrrolo[l,2-/]phenanthridine-3-carboxylate (216) directly, presumably via an intermediate of type (215).285... [Pg.386]

To palladium acetate (0.125 mmol) in 5 ml toluene was added tris(2,6-dimethoxyphenyl) phosphine (0.125 mmol), methyl phenylpropiolate (6.24 mmol) and trimethylsilylacety-lene (6.24 mmol) and the mixture stirred 16 hours. The product was purified by column chromatography using EthOAc/hexanes, 10 90, and isolated in 86% yield as a yellow oil. H-NMR data supplied. [Pg.63]

Triphenylstibine oxide. (CftH5).3Sb=0, reacts with dicyanoacetylene at room temperature, but no pure products could be isolated. Reaction with methyl propiolate at 115° gives methyl phenylpropiolate in 40% yield. [Pg.547]

Methyl phenylpropiolate reacts with the selenolate PhC=CSe to give the diselenole (224). The action of trifluoroacetic acid on the tellurium analogue PhC=CTe Na" results in a mixture of ( )- and (Z)-ditellurafulvenes (225). The bis(ditelluro)tetracene (226) has been prepared by treatment of the corresponding tetrachlorotetracene with sodium telluride. ... [Pg.233]

The complex 628 is converted into the benzo[phenyl isocyanide produces cyclopentano[ ]quinolines by way of a radical addition to the isocyanide, followed by two cyclizations (equation 63). ... [Pg.360]


See other pages where Methyl phenylpropiolate is mentioned: [Pg.231]    [Pg.145]    [Pg.159]    [Pg.368]    [Pg.192]    [Pg.193]    [Pg.195]    [Pg.32]    [Pg.896]    [Pg.966]    [Pg.368]    [Pg.896]    [Pg.966]    [Pg.351]    [Pg.32]    [Pg.328]    [Pg.18]    [Pg.259]    [Pg.351]    [Pg.136]    [Pg.300]    [Pg.257]    [Pg.76]    [Pg.52]   
See also in sourсe #XX -- [ Pg.547 ]

See also in sourсe #XX -- [ Pg.575 ]

See also in sourсe #XX -- [ Pg.122 ]




SEARCH



© 2024 chempedia.info