Carbonylation alkyne terminations

Alkynes undergo stoichiometric oxidative reactions with Pd(II). A useful reaction is oxidative carboiiyiation. Two types of the oxidative carbonyla-tion of alkynes are known. The first is a synthesis of the alkynic carbox-ylates 524 by oxidative carbonylation of terminal alkynes using PdCN and CuCh in the presence of a base[469], Dropwise addition of alkynes is recommended as a preparative-scale procedure of this reation in order to minimize the oxidative dimerization of alkynes as a competitive reaction[470]. Also efficient carbonylation of terminal alkynes using PdCU, CuCI and LiCi under CO-O2 (1 I) was reported[471]. The reaction has been applied to the synthesis of the carbapenem intermediate 525[472], The steroidal acetylenic ester 526 formed by this reaction undergoes the hydroarylalion of the triple bond (see Chapter 4, Section 1) with aryl iodide and formic acid to give the lactone 527(473],... 

Thiourea was used as stabilising agent for zerovalent Pd species [117]. The Pd-thiourea (H2NCSNH2) catalysed carbonylation of terminal alkynes and allylic alcohols has been described by Chiusoh [118]. More recently, Pd-thiourea-catalysed carbonylative annulation was studied. The reaction proceeds between alkynes, iodophenol acetates and carbon monoxide, in the presence of dppp, thiourea (H2NCSNH2) and base at 40 °C. Flavones have been obtained in good yields (Scheme 30) [119]. 

Carbonylation of alkynes is a convenient method to synthesize various carbonyl compounds. Alper et al. found that carbonylation of terminal alkynes could be carried out in aqueous media in the presence of 1 atm CO by a cobalt catalyst, affording 2-butenolide products. This reaction can also be catalyzed by a cobalt complex and a ruthenium complex to give y-keto acids (Scheme 4.8).92... 

Later, a nickel-catalyzed cascade conversion of propargyl halides and propargyl alcohol into a pyrone in water was reported. The reaction involved a carbonylation by CO and a cyanation by KCN (Eq. 4.55).96 Recently, Gabriele et al. explored a facile synthesis of maleic acids by palladium catalyzed-oxidative carbonylation of terminal alkynes in aqueous DME (1,2-dimethoxyethane) (Eq. 4.56).97... 

The palladium-catalyzed carbonylation of terminal alkynes with diphenyl diselenide under pressurized carbon monoxide (15 atm) proceeds successfully to give the corresponding selenoesters in high yields (Scheme 15.87) [161]. The carbonylation is completely regioselective and highly stereoselective. Similar carbonylation does not, unfortunately, proceed with diteUurides. 

Analogous high-pressure carbonylations of terminal as well as internal alkynes in the presence of PtH(SnCl3) (PPh3)2 have been describedi. Treatment of phenylacetylene with carbon monoxide in the presence of cobalt(II) chloride, potassium cyanide and nickel(II) cyanide under phase-transfer conditions gave a mixture of the acids 257 and 258, in which... 

Carbamates and ureas are easily prepared and separated from the oxidative carbonylation of amines catalyzed by [PdCl2(phenanthroline)] dissolved in [G4GiIm]BF4. The carbonylation of terminal 3-alkyn-l-ols and l-alkyn-4-ols by palladium acetate/2-(diphenylphosphino)pyridine dissolved in [G4CiIm]PF6 or [C4CiIm]BF4 affords quantitatively and selectively v< -a-methylene (Scheme 21) and 7- and -lactones, respectively. ... 

Reaction of various terminal alkynes using PdCl2 and CuCl2 in the presence of a base affords the alkynic esters 310 in satisfactory yields (path a) [122]. Carbonylation of terminal alkynes proceeds smoothly using Pd(OAc)2, hydroquinone and heteropolyacid (molybdovanadophosphate, NPMoV) in the presence of MeSOsH under oxygen at room temperature. Different products are obtained depending on the solvents. In MeOH, the acetylenic ester 311 was obtained (path a), but a-alkylmaleic anhydride 312 was obtained in dioxane (path c) [125]. 

B. Pd-CATALYZED TANDEM AND CASCADE CARBOPALLADATION OF ALKYNES TERMINATED BY CARBONYLATION... 

Ishii and colleagues developed a multicatalytic system for the oxidative carbonylation of terminal alkynes [85]. In the presence of Pd(OAc)2, chlorohydro-quinone and NPMoV, under CO and O2, acetylenecarboxylate or phenylmaleic... 

There are other examples of carbonylation of terminal alkynes, which involve the in-termolecular reaction of an acylpalladium complex with an alkyne moiety, but they most probably also involve carbon-carbon bond formations via cross-coupling rather than acylpalladation (Scheme 21). 

Oxidative Carbonylation ofAlkynes. Terminal alkynes are car-bonylated to give acetylenecarboxylates using PdCl2 and CuCl2 as catalysts (eq 30). The acetylenecarboxylate in a /S-lactam has been prepared by this procedure and then converted to a 8-keto ester (eq 31). ... 

The carbonylation of terminal 3-alkyn-l-ols and l-alkyn-4-ols by Pd(OAc)2 associated with 2-(diphenylphosphino)pyridine (2-PyPPh2) in BMI BF4 quantitatively and... 

Coperet, C., Ma, S., Sugihara, T. and Negishi, E. (1996) Cyclic carbopaUadation of alkynes terminated by carbonylative amidation. Tetrahedron, 52, 11529-11544. 

One of the first applications of this electrochemical methods, palladium catalyzed, was been the carbonylation of terminal alkynes. Terminal acetylenes were carbonylated imder very mild conditions to yield acetylenecarboxylates under atmospheric pressme of carbon monoxide at room temperature using palladium(II) catalyst in combination with its anodic recycling at graphite electrodes. [4]... 

Alper and Yu in 2007 developed the palladium-catalyzed highly substituted endocyclic enol lactone synthesis via the carbonylation of terminal alkyne and 1,3-diketones in an ionic hquid system (Table 15.21) [29]. Thirteen examples have been isolated under this process. It should be noted that this catalytic system can be recycled five times with only modest loss of its catalytic activity. 

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