Carbonylative phenylacetylene

Iridium-oxygen heterocycles have been synthesized as described above viz. isocyanide insertion into an Ir—O bond <88JA3704 , by carbonylative phenylacetylene insertion between an Ir—O bond <90JA9627> and by samarium-diiodide-induced cyclization of (44) (Equation (6)) <900M1713>. 

As an application of maleate formation, the carbonylation of silylated 3-butyn-l-ol affords the 7-butyrolactone 539[482], Oxidative carbonylation is possible via mercuration of alkynes and subsequent Lransmetallation with Pd(II) under a CO atmosphere. For example, chloromercuration of propargyl alcohol and treatment with PdCF (1 equiv.) under 1 atm of CO in THF produced the /3-chlorobutenolide 540 in 96% yield[483]. Dimethyl phenylinale-ate is obtained by the reaction of phenylacetylene, CO, PdCU, and HgCl2 in MeOH[484,485]. 

The carbonylation of aryl iodides in the presence of terminal alkynes affords the acyl alkynes 565. Bidentate ligands such as dppf give good results. When PhjP is used, phenylacetylene is converted into diphenylacetylene as a main product[4l5]. Triflates react similarly to give the alkynyl ketones 566[4I6], In... 

J-unsaturated ester is formed from a terminal alkyne by the reaction of alkyl formate and oxalate. The linear a, /J-unsaturated ester 5 is obtained from the terminal alkyne using dppb as a ligand by the reaction of alkyl formate under CO pressure. On the other hand, a branehed ester, t-butyl atropate (6), is obtained exclusively by the carbonylation of phenylacetylene in t-BuOH even by using dppb[10]. Reaction of alkynes and oxalate under CO pressure also gives linear a, /J-unsaturated esters 7 and dialkynes. The use of dppb is essen-tial[l 1]. Carbonylation of 1-octyne in the presence of oxalic acid or formic acid using PhiP-dppb (2 I) and Pd on carbon affords the branched q, /J-unsatu-rated acid 8 as the main product. Formic acid is regarded as a source of H and OH in the carboxylic acids[l2]. 

The direct combination of selenium and acetylene provides the most convenient source of selenophene (76JHC1319). Lesser amounts of many other compounds are formed concurrently and include 2- and 3-alkylselenophenes, benzo[6]selenophene and isomeric selenoloselenophenes (76CS(10)159). The commercial availability of thiophene makes comparable reactions of little interest for the obtention of the parent heterocycle in the laboratory. However, the reaction of substituted acetylenes with morpholinyl disulfide is of some synthetic value. The process, which appears to entail the initial formation of thionitroxyl radicals, converts phenylacetylene into a 3 1 mixture of 2,4- and 2,5-diphenylthiophene, methyl propiolate into dimethyl thiophene-2,5-dicarboxylate, and ethyl phenylpropiolate into diethyl 3,4-diphenylthiophene-2,5-dicarboxylate (Scheme 83a) (77TL3413). Dimethyl thiophene-2,4-dicarboxylate is obtained from methyl propiolate by treatment with dimethyl sulfoxide and thionyl chloride (Scheme 83b) (66CB1558). The rhodium carbonyl catalyzed carbonylation of alkynes in alcohols provides 5-alkoxy-2(5//)-furanones (Scheme 83c) (81CL993). The inclusion of ethylene provides 5-ethyl-2(5//)-furanones instead (82NKK242). The nickel acetate catalyzed addition of r-butyl isocyanide to alkynes provides access to 2-aminopyrroles (Scheme 83d) (70S593). 

The above rathenium carbonyl gives low yield (<5%) for the hydroamination of phenylacetylene with PhNH2 [307]. An important breakthrough was obtained by using the same catalyst in the presence of additives, especially strong acids (HPFj, HBF4) or their ammonium salts, to give the aromatic ketimines (Eq. 4.89) [307]. 

A combination of Co-mediated amino-carbonylation and a Pauson-Khand reaction was described by Pericas and colleagues [286], with the formation of five new bonds in a single operation. Reaction of l-chloro-2-phenylacetylene 6/4-34 and dicobalt octacarbonyl gave the two cobalt complexes 6/4-36 and 6/4-37 via 6/4-35, which were treated with an amine 6/4-38. The final products of this domino process are azadi- and azatriquinanes 6/4-40 with 6/4-39 as an intermediate, which can also be isolated and separately transformed into 6/4-40 (Scheme 6/4.11). 

Cyclopentenones. Reaction of the cyclopropylcarbene complex 1 with di-phenylacetylene in 1% aqueous dioxane results in the cyclopentenone 2 as the major product. The carbonyl group of 2 is derived from a CO ligand of 1, and C,... 

Oligomerization and polymerization of terminal alkynes may provide materials with interesting conductivity and (nonlinear) optical properties. Phenylacetylene and 4-ethynyltoluene were polymerized in water/methanol homogeneous solutions and in water/chloroform biphasic systems using [RhCl(CO)(TPPTS)2] and [IrCl(CO)(TPPTS)2] as catalysts [37], The complexes themselves were rather inefficient, however, the catalytic activity could be substantially increased by addition of MesNO in order to remove the carbonyl ligand from the coordination sphere of the metals. The polymers obtained had an average molecular mass of = 3150-16300. The rhodium catalyst worked at room temperature providing polymers with cis-transoid structure, while [IrCl(CO)(TPPTS)2] required 80 °C and led to the formation of frani -polymers. 

A palladium-catalysed carbonylative Sonogashira coupling was successfully carried out in the same setup [35]. Aryl iodides and phenylacetylene were submitted... 

In the metal carbonyl catalysts, the use of a catalytic amount of Ph2CCl2 enables the omission of CGI4. For example, the polymerization of phenylacetylene with W(CO)6 in the presence of Ph2GGl2 in toluene upon photoirradiation proceeds homogeneously to give a polymer with of ca. 2 x 127,128 MW polymers > 10 ) are attainable from sterically bulky aromatic and aliphatic acetylenes. It is also effective to use a catalytic amount of Lewis acids instead of GGI4 in the M(GO)6-based catalysts (M = W, Mo). ... 

Furane derivatives were also prepared by the carbonylation of acetylene derivatives. Phenylacetylene was converted to the furanone derivative shown in 3.35. under reductive conditions, while in the presence of oxygen 2-phenylmaleic anhydride was isolated as the main product.43... 

Hydration of alkynes yields carbonyl compounds and the ketone used in pyrylium syntheses has been successfully replaced by an alkyne (65CB334). Phenylacetylene, for example, reacts with 3-chloro-l-phenylprop-2-en-l-one to yield the 2,6-diphenylpyrylium salt. 

By knowing (or estimating) the pKa of a proton to be removed, it is possible to choose a base with a higher p Ka in order to have essentially complete conversion to the anionic carbon nucleophile. When these conditions are met, proton exchange occurs readily and a carbon nucleophile is produced. It must be remembered, however, that many bases can serve as nucleophiles. If the structural feature which acidified the C-H proton is an electrophile, then a nucleophilic base cannot be used. For example, butyl lithium (pKa > 45) converts phenylacetylene (pKa 25) smoothly to its conjugate base by proton removal, whereas it reacts as a nucleophile with the carbonyl group of acetophenone in spite of the fact that die a protons of acetophenone have pKa = 21 and are thus more acidic than the terminal proton in phenylacetylene. 

Concluding this part it must be stated that the addition of 11 across the carbonyl moiety in presence of quaternary ammonium fluorides has been achieved179. Benzaldehyde (242) and phenyl-TMS-acetylene (11) form (a-trimethylsiloxybenzyl)-phenylacetylene (259). 

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],... 

Commercially available 2m Me2Zn in toluene has been found able to promote the addition of phenylacetylene to aldehydes and ketones.102 This reactivity was determined by a new, unprecedented mechanism, which involves activation of the zinc reagent via coordination with carbonyl substrates that behave ligand like . 

The amount of the substitution products 362 and 363 was reduced in the presence of p-DNB, while the yield of 365 was unaffected. The formation of 365 was ascribed to the reversible addition of the conjugated base of the elimination product phenylacetylene 364 to the ketone carbonyl. This step is likely to be reversible and will gradually allow the buildup of the substitution products by addition of the nucleophile to 364, as an alternative route to the S l process353. 

Thermal reactions of the iodonium enolate 279 with acetonitrile and carbon disulfide in the presence of Cu(acac)2 lead to the heterobicyclic ketones 285 and 286, respectively (98TL9073), while similar treatment of the hybrid sulfonyl-carbonyl ylide 287 with CS2 or phenylacetylene affords the tricyclic sulfones 288 and 289 (97T9365). 

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