Carbonylation alkenyl iodide

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 substrates with the alkenyl iodide (138-141) moiety could be totally converted into the desired products (138a, 139a, 138b-140b, 138c-141c) in4-8 h, while the enol triflate (142) reacted slowly. The bromo derivative (144) is unreactive and no carbonylation product was observed even after prolonged reaction times. 

The carbonylation of the same substrates (138-144) with several A-substituted hydrox-ylamines proceeds with the same order of substrate reactivity (Scheme 67). In particular, with steroidal alkenyl iodides 138-141 and enol triflates 142 and 143 complete conversion of the substrates could be achieved, in the latter cases (142 and 143) with long reaction times. The analogue bromo derivative 144 is completely unreactive. 

Lithium triethyl(l-methylindolyl-2)borate has been introduced as a convenient source of indolyl residue for carbonylative cross-coupling with aryl iodides, alkenyl iodides, or triflates. The reaction requires elevated CO pressure and high loading of catalyst (5mol.%) (Equation (15)). Aryl and alkenyl bromides, as well as aryl iodides... 

Formation of aldehydes. Aldehydes can be prepared by the carbonylation of halides in the presence of various hydride sources. The carbonylation of aryl and alkenyl iodides and bromides with CO and H (1 1) in aprotic solvents in the presence of tertiary amines affords aldehydes[373,374]. Aryl chlorides, as tricarbonylchromium derivatives, are converted into aldehydes at 130 C[366], Sodium formate can be used as a hydride source to afford aldehydes. Chlorobenzene (514) was carbonylated at 150 °C to give benzaldehyde with CO and sodium formate by using dippp as a ligand[375,376]. 

The alkenylzirconium compound 314 is prepared by hydrozirconation of 1-heptyne (312) with hydrozirconocene chloride (313), and reacts with alkenyl iodide to afford the 1,3-diene 315 [138]. The Zr reagent can be used even in the presence of carbonyl group, which is sensitive to A1 or Mg reagents. 

Scheme 70 Pd(0)/light-catalyzed multiple carbonylations of 4-alkenyl iodides...

Double carbonylation As a radical mediator in the carbonylation of 4-alkenyl iodides, BujGeH behaves differently from BUjSnH, because it is a slower hydrogen donor, giving the second acyl radical time to react with the cyclic ketone, which was formed in the first step. Instead of the keto aldehydes, fused y-lactones become the major products. 

Alkenyl halides and trifiates are easily carbonylated. Carbonylation of a-iodo enone 3 proceeded at 60 °C using Pd(OAc)2 and DPPP, and the ester 4 was obtained in 62% yield [6]. The lactam 5 was converted to the vinyl trifiate 6, which was carbonylated to afford the a, -unsaturated ester 7 [7], Carbonylation of the alkenyl iodide 8, possessing a labile peroxy group proceeded smoothly to give the a, -unsaturated ester 9 under 1 atm of CO at 60 °C in DMF. The peroxy group remained intact [8]. 

Alkenyl iodides can be generated in situ by hydroalumination of alkynes, followed by iodination, and a,jS-unsaturated esters are prepared by carbonylation without isolation of the iodide. As an example, the propargylic alcohol 10 was aluminated regio- and stereoselectively and converted to the alkenyl iodide 11. The intramolecular carbonylation of 11 afforded the dibutenolide 12 in 81 % yield. The reaction is a key step in the total synthesis of (-l-)-parviflorin [9]. 

Chen and Wang described a nickel-catalyzed carbonylative Negishi coupling reactions [82]. In the presence of a catalytic amount of nickel chloride and 4,4 -dimethoxyl-2,2 -bypyridyl under carbon monoxide atmosphere, various enones were produced from enol triflates and diorganozinc reagents (Scheme 4.44). They demonstrate that the rate of CO insertion is increased by the addition of lithium or magnesium halides and the use of polar solvents. Alkenyl iodides can also be used instead of enol triflates. 

Later, they extended their methodology to alkenylsilanes and alkenyl iodides. In 2001 Kang and his team reported on the carbonylative coupling of alkynyl-silanes with triarylantimony diacetates [85]. Alkynones were synthesized in good yields in the presence of a Pd catalyst and Cul at 50 °C (Scheme 4.46). 

Carbonylation of alkenyl iodides according to the above protocol was applied by Hoye and co-workers to the total synthesis of naturally occurring butenohdcs. An example from the synthesis of (+)-asimicin and (+)-bullacitin is shown in Scheme 4. 

S. Ho, G. Bondarenko, D. Rosa, B. Dragisic, A. Orellana, J. Org. Chem. 2012, 77, 2008-2012. Synthesis of acyl pyrroles via palladium-catalyzed carbonylative amination of aryl and alkenyl iodides. 

Intramolecular [80] and intermolecular [81,82] trapping of acylpalladium intermediates with enolates has been studied. Intermolecular versions can involve trapping with both C- and 0-enolates. The Pd-catalyzed carbonylation reactions of alkenyl iodides in the presence of various ketone enolate precursors displayed an interesting dichotomy the expected 0-enolate trapping product 47 may undergo cyclization to give six-membered lactone 48, and the product s composition critically depends on the amount of a base and the structure of ketones (Scheme 9.19). 

Termination of cyclic carbopalladation of alkynes via carbonylative lactonization/ lactamization has been achieved with alkenyl iodides containing an ca oxydryl or amido/amino moiety [85]. 

The preparation of related carbonyl-containing alkenylmagnesium reagents has been reported by Hiemstra in the course of synthetic studies toward the synthesis of solanoedepin A [115,116]. The treatment of the cyclic alkenyl iodide 212 with iPrMgCl in THF at -78 °C furnished the desired Grignard reagent 213 that reacts with acrolein and catalytic amounts of CuBr- McjS in THF HMPA in the presence of TMSCI furnishing the Michael adduct 214 in 89% yield (Scheme 4.43) [116]. 

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]. 

Allylation of perfluoroalkyl halides with allylsilanes is catalyzed by iron or ruthenium carbonyl complexes [77S] (equation 119) Alkenyl-, allyl-, and alkynyl-stannanes react with perfluoroalkyl iodides 111 the presence ot a palladium complex to give alkenes and alkynes bearing perfluoroalkyl groups [139] (equation 120)... 

The carbonylation of o-diiodobenzene with a primary amine affords the phthalimide 501 [355,356], Carbonylation of iodobenzene in the presence of odiaminobenzene (502) and DBU or 2,6-lutidine affords 2-phenylbenzimida-zole (503)[357], The carbonylation of aryl iodides in the presence of pentafluor-oaniline affords 2-arylbenzoxazoles directly. 2-Arylbenzoxazole is prepared indirectly by the carbonylation of n-aminophenol[358]. The optically active aryl or alkenyl oxazolinc 505 is prepared by the carbonylation of the aryl or enol triflates in the presence of the opticaly active amino alcohol 504, followed by treatment with thionyl chloride[359]. 

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],... 

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