Iodides carbonylation

A half-metallocene iron iodide carbonyl complex Fe(Cp)I(CO)2 was found to induce the living radical polymerization of methyl acrylate and f-bulyl acrylate with an iodide initiator (CH3)2C(C02Et)I and Al(Oi- Pr)3 to provide controlled molecular weights and rather low molecular weight distributions (Mw/Mn < 1.2) [79]. The living character of the polymerization was further tested with the synthesis of the PMA-fc-PS and PtBuA-fi-PS block copolymers. The procedure efficiently provided the desired block copolymers, albeit with low molecular weights. 

An anionic rhodium iodide carbonyl complex was supported on polyvinylpyrrolidone for the carbonylation of methanol in the presence of scC02 [98], Depending on the reaction conditions and method of extraction, less than 0.08% rhodium leaching was observed. Saturation of the support with methyl iodide was found to be vital to enhance the longevity and recyclability of the catalyst. 

In the initial studies about the reaction of /V.zV-disubstituted formamides with alkaline metals to give glyoxylic amides, the participation of carbamoyl metal derivatives as intermediates was postulated83. The first preparation of the carbamoyllithium 77 was described two years later by a mercury-lithium transmetallation from compound 76 at —75 °C (Scheme 20)84. The authors proposed also an aminocarbene structure 78 and studied its reactivity with methanol, methyl iodide, carbonyl compounds, esters, acyl chlorides, mercury(II) chloride and tri-n-butyltin chloride providing compounds 79. 

Dimethyl thiocarbamoyllithium (113) was generated at —100 °C in the absence of the electrophile by deprotonation of A,A-dimethylthioformamide (112) (Scheme 29)105. This intermediate was trapped with D20, methyl iodide, carbonyl compounds and esters to provide the expected products 114. 

Benzodithioles 285 (R1 = H) and 7,8-dimethyl-l,5-dihydro-2,4-benzodithiepins286 (R = H) have been used as precursors of formyl and acyl anion derivatives. The lithiation of compounds 285 takes place at —30 °C with n-BuLi and these anions are stable for long periods of time at this temperature454. They react with alkyl iodides, carbonyl compounds and epoxides, the addition to cyclohex-2-enone taking place at the carbonyl group. The deprotection has also been carried out with mercury(II) oxide and BF3 OEt2-... 

BP AcOH Ir [lr(CO)2l2]H" Mel/iodide salts, metal carbonyls (i.e., Ru iodide carbonyls... 

Further development of iridium-complex catalysts was initiated by BP Chemicals in the 1990s, with the hope of identifying reaction conditions under which high activity and selectivity could be achieved. An additional aim was to develop a catalyst that is more robust in the presence of low water concentrations than the rhodium complex catalyst thus, some similarity to the Celanese lithium-iodide stabilized rhodium catalyst was sought. A series of patents provide detail of the discovery by BP of promoters that enhance the activity of an iridium/iodide carbonylation catalyst and, crucially, attain optimum rate at relatively low water concentrations, as illustrated in Figure 2 [116-119]. 

In a new procedure, several 3-substituted diazepam derivatives (124) have been prepared, in moderate to good yields, by allowing metallated diazepams (123) to react with alkyl iodides, carbonyl compounds, or esters. Two equivalents of lithium di-isopropylamide (LDA) were required to produce an equilibrium concentration of (123) that was sufficiently high for synthetic use. ... 

Independently, Okamura and colleagues generated racemic a-lithiated-(x,P-unsaturated sulfoxides in the same way as Posner s group and reported their reactions with methyl iodide, carbonyl compounds, and epoxides [48.49]. They also noted the configurational instability of such intermediates. Alkylation of the intermediates using butyl iodide or benzyl bromide gave low yields of products. 

Fallacious acetate I triphenylphosphine I sodium salt Carboxylic acid anhydrides from carboxylic acid salts and iodides Carbonylation under mild conditions... 

S. Bontemps, J. S. Quesnel, K. Worrall, B. A. Amdtsen, Angew. Chem. Int. Ed 2011, 50, 8948-8951. Palladium-catalyzed aryl iodide carbonylation as a route to imidazoline synthesis design of a five-component coupling reaction. 

Another feature of the Pd—C bonds is the excellent functional group tolerance. They are inert to many functional groups, except alkenes and alkynes and iodides and bromides attached to sp carbons, and not sensitive to H2O, ROH, and even RCO H. In this sense, they are very different from Grignard reagents, which react with carbonyl groups and are easily protonated. 

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],... 

Diene carboxylates can be prepared by the reaction of alkenyl halides with acrylates[34]. For example, pellitorine (30) is prepared by the reaction of I-heptenyl iodide (29) with an acrylate[35]. Enol triflates are reactive pseudo-halides derived from carbonyl compounds, and are utilized extensively for novel transformations. The 3,5-dien-3-ol triflate 31 derived from a 4,5-unsaturated 3-keto steroid is converted into the triene 32 by the reaction of methyl acrylate[36]. 

In the total synthesis of zearaienone (451), the ester 450 was prepared by the carbonylation of the crowded aryl iodide 448. The alkyl iodide moiety in the alcohol molecule 449 is not attacked[306]. Methyl trifluoromethacrylate (453) was prepared by the carbonylation of 3,3,3-trifluoro-2-bromopropylcne (452), The carbonylation in the presence of alkylurea affords 454. which is converted into the trifluoromethyluracil 455[307],... 

Usually, iodides and bromides are used for the carbonylation, and chlorides are inert. I lowever, oxidative addition of aryl chlorides can be facilitated by use of bidcntatc phosphine, which forms a six-membered chelate structure and increa.scs (he electron density of Pd. For example, benzoate is prepared by the carbonylation of chlorobenzene using bis(diisopropylphosphino)propane (dippp) (456) as a ligand at 150 [308]. The use of tricyclohexylphosphine for the carbonylation of neat aryl chlorides in aqueous KOH under biphasic conditions is also recommended[309,310]. 

The benzoic acid derivative 457 is formed by the carbonylation of iodoben-zene in aqueous DMF (1 1) without using a phosphine ligand at room temperature and 1 atm[311]. As optimum conditions for the technical synthesis of the anthranilic acid derivative 458, it has been found that A-acetyl protection, which has a chelating effect, is important[312]. Phase-transfer catalysis is combined with the Pd-catalyzed carbonylation of halides[3l3]. Carbonylation of 1,1-dibromoalkenes in the presence of a phase-transfer catalyst gives the gem-inal dicarboxylic acid 459. Use of a polar solvent is important[314]. Interestingly, addition of trimethylsilyl chloride (2 equiv.) increased yield of the lactone 460 remarkabiy[3l5]. Formate esters as a CO source and NaOR are used for the carbonylation of aryl iodides under a nitrogen atmosphere without using CO[316]. Chlorobenzene coordinated by Cr(CO)j is carbonylated with ethyl formate[3l7]. 

Heteroaromatic esters such as 493 and amides are produced by the carbo-nylation of heterocyclic bromides[347,348]. Even dichloropyrazine (494) and chloropyridine are carbonylated under somewhat severe conditions (120 C, 40 atm)[349]. The carbonylation of trifluoroacetimidoyl iodide (495) proceeds under mild conditions, and can be used for the synthesis of the trifluoromethyl-glycine derivatives 496 and 497(350]. 

The carbonylation of aryl iodides in the presence of alkyl iodides and Zn Cu couple affords aryl alkyl ketones via the formation of alkylzinc species from alkyl iodides followed by transmetallation and reductive elimination[380]. The Pd-catalyzed carbonylation of the diaryliodonium salts 516 under mild conditions in the presence of Zn affords ketones 517 via phenylzinc. The a-diketone 518 is formed as a byproduct[381],... 

The reaction of alkenyl iodides or triflates, alkenylstannanes, and CO affords divinyl ketones[397,398]. Thus the capnellene skeleton 538 has been synthesized by the carbonylation of the cyclopentenyl triflate 536 with the alkenyltin 537[392], The macrocyclic divinyl ketone 540 has been prepared in a moderate yield by the carbonylative cyclization of 539[399]. 

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... 

Particularly alkyl halides which have a perfluoroalkyl group at the /3-position undergo smooth carbonylation. Probably the coordination of fluorine to form a five-membered chelate ring accelerates the reaction. Double carbonylation to give the a-keto amide 915 is possible in Et NH with the fluorine-bearing alkyl iodide 914[769,770]. The ester 917 is obtained by the carbonylation of the /3-perfluoroalkyl iodide 916 in ethanol. 

Alkyl ketones can be prepared by the carbonylation of alkyl iodides in the presence of organoboranes. The carbonylation of iodocyclohexane with 9-octyl-9-BBN at 1 atm gives cyclohexyl octyl ketone in 65% yield[386]. This reaction is treated in Section 1.1.3.3. Methyl o-methylacetoacetate (919) is obtained by the reaction of the 2-bromopropionate 918, which has a /9-hydrogen, with CO and Me4Sn. PhjAs as a ligand gives better results than Ph3P[771]. 

It looks as though all that is needed is to prepare the acetylenic anion then alkylate it with methyl iodide (Section 9 6) There is a complication however The carbonyl group m the starting alkyne will neither tolerate the strongly basic conditions required for anion formation nor survive m a solution containing carbanions Acetyhde ions add to carbonyl... 

In 1968 a new methanol carbonylation process using rhodium promoted with iodide as catalyst was introduced by a modest letter (35). This catalyst possessed remarkable activity and selectivity for conversion to acetic acid. Nearly quantitative yields based on methanol were obtained at atmospheric pressure and a plant was built and operated in 1970 at Texas City, Tex. The effect on the world market has been exceptional (36). 

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

Cyclic Peroxides. CycHc diperoxides (4) and triperoxides (5) are soHds and the low molecular weight compounds are shock-sensitive and explosive (151). The melting points of some characteristic compounds of this type are given in Table 5. They can be reduced to carbonyl compounds and alcohols with zinc and alkaH, zinc and acetic acid, aluminum amalgam, Grignard reagents, and warm acidified iodides (44,122). They are more difficult to analyze by titration with acidified iodides than the acycHc peroxides and have been sucessfuUy analyzed by gas chromatography (112). 

A related but distinct rhodium-catalyzed methyl acetate carbonylation to acetic anhydride (134) was commercialized by Eastman in 1983. Anhydrous conditions necessary to the Eastman acetic anhydride process require important modifications (24) to the process, including introduction of hydrogen to maintain the active [Rhl2(CO)2] catalyst and addition of lithium cation to activate the alkyl methyl group of methyl acetate toward nucleophilic attack by iodide. 

The introduction of tritium into molecules is most commonly achieved by reductive methods, including catalytic reduction by tritium gas, PH2], of olefins, catalytic reductive replacement of halogen (Cl, Br, or I) by H2, and metal pH] hydride reduction of carbonyl compounds, eg, ketones (qv) and some esters, to tritium-labeled alcohols (5). The use of tritium-labeled building blocks, eg, pH] methyl iodide and pH]-acetic anhydride, is an alternative route to the preparation of high specific activity, tritium-labeled compounds. The use of these techniques for the synthesis of radiolabeled receptor ligands, ie, dmgs and dmg analogues, has been described ia detail ia the Hterature (6,7). 

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