Alkynes reactions with carbon monoxide

Finally, manganese carbonyl complexes also show potential for effecting interesting phase transfer catalyzed carbonylation reactions. Alkynes react with carbon monoxide and methyl iodide in methylene chloride, using 5N NaOH as the aqueous phase, benzyl-triethylammonium chloride as the phase transfer catalyst, and either bromopentacarbonylmanganese or dimanganese decacarbonyl to afford... 

Alkenes can be converted to succinic esters by reaction with carbon monoxide, an alcohol, and palladium chloride in the presence of mercuric chloride.1,12 The addition is mostly syn. In similar reaction, both terminal and internal alkynes can be converted to esters of maleic acid. 

We have concentrated on palladium because it is the most important of the transition metals but we must not leave you with the idea that it is the only one. We shall end with two reactions unique to cobalt—the Pauson-Khand reaction that we mentioned right at the start of the chapter and the Vollhardt co-trimerization. You will sec at once that cobalt has a special affinity with alkynes and with carbon monoxide. 

Treatment of monosubstituted acetylenes with alkanethiols under an atmosphere of carbon monoxide gives j8-alkyl-a,jS-unsaturated aldehydes in reasonable yields (equation 11). A mechanistic scheme where the alkanethiyl radical adds to the alkyne to give the jS-(alkylthio)vinyl radical followed by the reaction with carbon monoxide has been indicated as the key steps in these radical chain reactions. Only the thermodynamically stable (E)-isomer of the carbonylation product was obtained, probably due to a postisomerization process. 

E-Alkenylpentafluorosilicates (21), readily prepared by hydrosilylation of alkynes, react with carbon monoxide (20 C, 1 atm) in the presence of palladium salts and sodium acetate-methanol to give the -a,/3-unsaturated carboxylic ester (22) in excellent yield and with high stereoselectivity. The reaction can tolerate other functional groups, such as esters and ethers. 

The conversion of acetylenes into olefinic esters by use of addition reactions has been illustrated by the following two examples, (i) 1-Alkenyl boranes, which are readily prepared by the hydroboration of alkynes, are converted into a,fi-unsaturated carboxylic esters in good yield by reaction with carbon monoxide in the presence of palladium chloride and sodium acetate in methanol the process is carried out at atmospheric pressure and occurs with retention of configuration with respect to the alkenyl borane. (ii) Carboxylic acids add to acetylenes in the presence of silver carbonate to provide a novel synthesis of enol esters, which are formed in an 8 2 mixture of isomers. ... 

Transmetallation of 1-6 or treatment of 1-6 with Lewis acid further broadens the scope of its reaction chemistry. In the presence of CuCl, the reaction of 1-6 with diazo dicarboxylate affords pyridazine derivatives [27]. In the presence of CuCl or nickel complexes, the reaction of 1-6 with alkynes leads to benzene derivatives [28, 29]. Transmetallation of 1-6 with Bids allows further reaction with 2-oxo malonate to give 2/7-pyran derivatives [27]. Transmetallation of 1-6 with CrCls followed by reaction with isocyanates affords pyridine derivatives [30]. Transmetallation of 1-6 with AICI3 followed by reaction with aldehydes affords pentasubstimted cyclo-pentadiene derivatives [31]. Under the similar condition, 1-6 reacts with nitroso compounds to form pyrrole derivatives [32]. Addition of n-butyl lithium activates 1-6 and allows further reaction with carbon monoxide, which leads to carbonylation and affords 2-cyclopentenone upon hydrolysis [33]. 

The carbonylative macrocydization using acyl chlorides and diloroformates as substrates represents an interesting tool for the synthesis of cyclic ketones, lactones, a,/3-unsaturated esters. A complementary approach is based on the carbonyl insertion reaction with carbon monoxide and subsequent cross-coupling as exemplified by the approach to the core structure of Phomactins C and D, with an alkyne-enoltriflate carbonylative coupling as the key macrocydization step [131] (Scheme 6.17). 

CO. Alkynes will react with carbon monoxide in the presence of a metal carbonyl (e.g. Ni(CO)4) and water to give prop>enoic acids (R-CH = CH-C02H), with alcohols (R OH) to give propenoic esters, RCH CHC02R and with amines (R NH2) to give propenoic amides RCHrCHCONHR. Using alternative catalysts, e.g. Fe(CO)5, alkynes and carbon monoxide will produce cyclopentadienones or hydroquinols. A commercially important variation of this reaction is hydroformyiation (the 0x0 reaction ). 

The thermal benzannulation of Group 6 carbene complexes with alkynes (the Dotz reaction) is highly developed and has been used extensively in synthesis [90,91]. It is thought to proceed through a chromium vinylketene intermediate generated by sequential insertion of the alkyne followed by carbon monoxide into the chromium-carbene-carbon double bond [92]. The realization that photodriven CO insertion into Z-dienylcarbene complexes should generate the same vinylketene intermediate led to the development of a photochemical variant of the Dotz reaction (Table 14). 

The bidentate formate ligand of OsH(K2-02CH)(CO)(P,Pr3)2 is converted into a monodentate group by carbonylation. Thus, the reaction of this compound with carbon monoxide gives 0sH K1-0C(0)H (C0)2(P Pr3)2. Similarly, the addition of a stoichiometric amount of trimethylphosphite yields 0sH k -0C(0)H (C0) P(OMe)3 (P Pr3)2, and the addition of a stoichiometric amount of ethyne di-carboxylic methyl ester leads to 0sH K1-0C(0)H (C0)(r 2-Me02CC=CC02Me) (P Pr3)2, which in solution partially dissociates the alkyne. As is shown in... 

Abstract The transition metal mediated conversion of alkynes, alkenes, and carbon monoxide in a formal [2 + 2+1] cycloaddition process, commonly known as the Pauson-Khand reaction (PKR), is an elegant method for the construction of cyclopentenone scaffolds. During the last decade, significant improvements have been achieved in this area. For instance, catalytic PKR variants are nowadays possible with different metal sources. In addition, new asymmetric approaches were established and the reaction has been applied as a key step in various total syntheses. Recent work has also focused on the development of CO-free conditions, incorporating transfer carbonylation reactions. This review attempts to cover the most important developments in this area. 

The intramolecular 2 - - 2 - - 1-cycloadditions of allene, alkyne (106), and carbon monoxide yield a -methylene-(107) or 4-alkylidene-cyclopentenones (108) depending on the allene structure or the reaction conditions (Scheme 4i).i59.i6o The cobalt-catalysed 4 - - 2 - - 2-cycloaddition of norbornadienes (109) with buta-1,3-dienes readily produces cycloadducts (110) when a bimetal system is used (Scheme A2) ... 

The electron-rich olefin (Eq. 11) [47] and alkyne (Eq. 12) [48] can react with elemental selenium to end up in the formation of diselenoesters and selenoamides. During the reaction of the former, several types of new species have been involved. As with the reaction of carbon monoxide with elemental selenium... 

The reaction is catalyzed by a mixture of H4Ru4(CO),2 and Co2(CO)g (THF, 120 C, 24 hr, CT 9) (382). Under phase-transfer conditions, y-keto acids can be obtained from terminal alkynes, methyl iodide, carbon monoxide, and water using a 1 1 mixture of Co2(CO)8 and Ru3(CO),2 in a benzene-sodium hydroxide solution with dodecyltrimethylammonium chloride (200°C, 1 bar, the yield and catalytic turnover were not reported) (383) ... 

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