Phenylacetylene alkenylation with

Tandem cyclization/3-substitution can be achieved starting with o-(trifluoro-acetamido)phenylacetylenes. Cyclization and coupling with cycloalkenyl trif-lates can be done with Pd(PPh3)4 as the catalyst[9]. The Pd presumably cycles between the (0) and (II) oxidation levels by oxidative addition with the triflate and the reductive elimination which completes the 3-alkenylation. The N-protecting group is removed by solvolysis under the reaction conditions, 3-Aryl groups can also be introduced using aryl iodides[9]. 

The reactivity of OsHCl(CO)(P Pr3)2 toward alkynes depends on the type of alkyne used. Whereas phenylacetylene, propyne, and acetylene react by insertion to give the five-coordinate alkenyl derivatives Os ( >CI I=CHR Cl(CO)(PIPr3)2 (R = Ph, Me, H),31,33 the reaction with methylpropiolate affords a mixture of Os C(=CH2)C(OMe)0 Cl(CO)(P,Pr3)2 and 0s ( )-CH=CHC02Me Cl(C0) (P Pr3)234 (Scheme 3), and tert-butyl acetylene and diphenylacetylene are inert. 

Recently, a proposal has been put forth that a /raor-addition process may be possible through dinuclear ruthenium intermediates.34 As shown in Scheme 5, reaction of tetraruthenium aggregate A with phenylacetylene results in the fully characterized bridging dinuclear alkenyl complex B. The authors propose a direct /ra .r-dclivcry of hydride through a dinuclear intermediate may be active in the hydrosilylation catalyzed by A, though compound B itself is unreactive to Et3SiH. 

Friedel-Crafts alkenylation of arenes with various phenylacetylenes to yield 1,1-diarylalkenes was reported. Alkyl-substituted benzenes and naphthalene react with phenylacetylene in the presence of zeolite HSZ-360 to afford the products in good to excellent yields and selectivities 415... 

The carbonylation of aryl iodide in the presence of terminal alkynes affords acyl alkynes. Bidentate ligands such as DPPF give good results [241]. When PI13P is used, phenylacetylene is mainly converted to diphenylacetylene. The alkynyl ketones 488 are prepared by the reaction of the alkenyl triflate 487 with phenylacetylene and CO [242],... 

Intermolecular additions of alcohols to alkynes can be coupled with other tandem reactions of the alkenyl-gold intermediate. Thus, reaction between salicylaldehyde and phenylacetylenes can give access to the isoflavanone skeleton (equation 7), whereas a three-component addition of methylenecylopropylcarbinols, arylalkynes, and alcohols leads to bicyclic compounds (equation 8). ... 

Similarly to 1, complex 20 reacts with terminal alkynes such as acetylene and phenylacetylene to give the corresponding alkenyl derivatives Os ( )-CH=CHR Cl(CO)(PiPr3)2 (R = H (21a), Ph (21b)) (Scheme 6). The structure of the styryl derivative 21b has been determined by X-ray diffraction analysis [9]. The most remarkable features are, first, the square pyramidal coordination of the metal with the alkenyl ligand in the apex and, second, the -stereochemistry of the styryl group. 

In contrast to the reaction with phenylacetylene, the treatment of 190 with 2 equiv of methyl propiolate leads to the alkenyl-alkynyl compound 200 (Scheme 55). The use of a 1 1 molar ratio of alkyne to osmium complex gives the same product along with unreacted dihydride-dihydrogen complex [79]. The addition of a toluene solution of HCl to a toluene solution of 200 produces the carbon-carbon coupling of the alkynyl and alkenyl fragments to give selectively the... 

Although the catalytic activity of the alkenyl acetate compounds previously mentioned have not been studied, Kawano et al. have recently shown that the triphenylphosphine derivative Ru C(=CHPh)0C(0)Et Cl(C0)(PPh3)2 catalyzes the addition of propanoic acid to phenylacetylene to give (Z)-2-phenylethenyl propanoate, selectively. This complex is prepared by reaction of RuC1(k2-02CEt)(C0)(PPh3)2 with phenylacetylene [84]. 

Electrophilic alkenylation. Arenes react with phenylacetylene over HZS-360 zeolite in 1,2-dichlorobenzene at 110° to give 1,1-diarylethenes (10 examples, 40-94%). 

Treatment of triazolopyiidine 132b with phenylacetylene in the presence of Rh(Il) acetate smoothly produced a mixture of cyclopropene 135 and indolizine 136. Cyclopropene 135 does not undergo further isomerization into indolizine 136 under these conditions (07AGE4757). However, the selectivity of the trans-annulation (136 over 135) could be dramatically improved by using rhodium(II) heptafluorobutyrate as catalyst. Thus, trans-annulation of 132b with a series of aryl and alkenyl alkynes proceed highly chemoselectively to produce indolizines 136. Electron-rich, electron-deficient and sterically hindered aryl alkynes are nearly equally effective (Scheme 31). 

The interaction of 32 with unsaturated organic substrates has also been explored, once again revealing reluctance for insertion of alkenes or alkynes into the Co-C linkage. Only for phenylacetylene was any reaction observed, affording after hydrolysis an isomeric mixture of cis- and rra -1-phenyl-1-butene in 68% yield (Scheme 3). These products were presumed to arise from initial alkyne insertion into the Co-Et bond, with subsequent protonolysis of the Co-C alkenyl linkage. ... 

Sonogashira coupling of o-iodothioanisole (73) with phenylacetylene affords o-(l-alkynyl)thioanisole 74, which cyclizes to give 2-substituted 3-iodobenzothio-phene 75 by the treatment with iodine. Furthermore, Suzuki coupling of 75 affords the 2,3-disubstituted benzothiophene 76 [45]. The iminoalkyne 78 is prepared by Sonogashira coupling of the alkenyl iodide 77, and the substituted pyridine 79 is obtained by the Cul-catalyzed cyclization [46]. 

Butyllithium (1.5 M in hexane) added to a soln. of phenylacetylene in THF at 0°, warmed to room temp., solvent removed in vacuo, cooled to —50°, the obtained Li-acetylide dissolved in THF, treated with 1 eq. ClTi(OPr-/)3 (1.59 Min THF), a 1 M soln. of styrene oxide in THF added at —50°, warmed to room temp, within 2 h, stirred for 3 days, and hydrolyzed with 1 AHCl - 2,4-diphenyl-3-butyn-l-ol. Y 70%. Alkyloxiranes gave only 10% of the expected product. F.e. inch ring opening of alkenyl-, alkynyl-, and trimethylsilyl-oxiranes, s. N. Krause, D Seebach, Chem. Ber. 121, 1315-20 (1988). 

Ru (Tp)(Cl)(PPh3)(MeCN)] serves as a starting material for the synthesis of new ruthenium complexes. Water was also involved in the reactions of this Ru—Tp complex with phenylacetylene and l-ethynyl-4-fluorobenzene that yields the alkenyl ketone compound [Ru(Tp)(PPh3)(C(CH2Ph)= CHC(O)Ph)] and the acyl complex [Ru(Tp)(PPh3)(C(0)CH2(C6H5)F)]. ... 

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