A general and efficient aldehyde decarbonylation reaction by using a palladium catalyst

Modak, A.; Deb, Arghya; Patra, Tuhin; Rana, Sujoy; Maity, Soham; Maiti, Debabrata

doi:10.1039/c2cc31144e

Cited by 175 publications

(124 citation statements)

References 32 publications

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“…The substrate 1 f with a gem-disubstituted olefin moiety smoothly underwent cyclization under Co-IPr catalysis to afford the six-membered ring 3 f with near complete regioselectivity (entry 1), presumably because formation of a quaternary carbon center through five-membered ring formation is unfavorable. [13] Both the E-and Z-olefin moieties smoothly participated in the reaction (entries 3 and 6), showing a relatively minor effect of the double-bond geometry on the reactivity and the regioselectivity. An alkyl substituent on the homoallylic terminus directed the reaction to give the fivemembered cyclic product (2 g-i) in preference to the sixmembered isomer regardless of the ligand used (entries 3-6).…”

Section: Methodsmentioning

confidence: 99%

“…[13] Along with the N-homoallylindole substrates, the substrate 1 m with a 2-vinylphenyl group also participated in sixmembered ring formation to afford the angularly fused tetracyclic product 3 m in 63 % yield (entry 10). Exclusive six-membered ring formation was also observed with the substrate 1 k bearing a substituent at the allylic position (entry 8).…”

Section: Methodsmentioning

confidence: 99%

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Cobalt‐Catalyzed Intramolecular Olefin Hydroarylation Leading to Dihydropyrroloindoles and Tetrahydropyridoindoles

2013

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Fused tricyclic indoles with dihydropyrroloindole and tetrahydropyridoindole core skeletons are present in pharmaceutically relevant small molecules, such as L-888,607, Ro 32-0432, and MK-7246 ( Figure 1). [1] The latter skeleton is also relevant to indole alkaloids, such as strychnine, brucine, and vincamine. Consequently, efficient and selective reactions allowing construction of such fused cyclic systems could be useful synthetic methods. As a notable example, the group of Bergman and Ellman achieved the synthesis of biologically active dihydropyrroloindole derivatives, including a chiral non-racemic derivative, through rhodium-catalyzed, aldimine-directed C À H activation/intramolecular hydroarylation of N-allylindoles (Scheme 1 a). [2] Along with this particular example, they have extensively developed rhodium-catalyzed CÀH activation reactions of aromatic, heteroaromatic, and olefinic substrates bearing alkene tethers [3][4][5][6] and demonstrated their utility in target-oriented synthesis of carbo-and heterocycles, [7] while the Murai group earlier reported seminal studies on rhodium-and ruthenium-catalyzed intramolecular cyclization of 1,5-and 1,6-diene derivatives through chelation-assisted olefinic CÀH activation. [8] As shown in Scheme 1 a, the rhodium catalysis works most efficiently for 5-endo-type cyclization with substrates bearing allylic tethers. On the other hand, homoallylic tethers pose a regioselectivity issue because of the two intrinsically feasible modes of cyclization (that is, 5-exo vs. 6-endo) as well as facile olefin isomerization prior to hydroarylation, and have not been employed on the indole platform. Alkene tethers that are longer than a homoallyl group have not been used on any aromatic or heteroaromatic platforms. [9] We report herein on our development of cobalt-N-heterocyclic carbene (NHC)catalyzed intramolecular olefin hydroarylation of indole substrates bearing homoallyl or bishomoallyl tethers. Complementing the scope of the rhodium catalysis, the present catalytic systems allow 5-exo-, 6-endo-, and 6-exo-type cyclization to afford a series of dihydropyrroloindole and tetrahydropyridoindole derivatives under mild reaction conditions. The present study has led to a couple of notable findings, namely, 1) regiodivergent formation of five-and sixmembered rings by the choice of the NHC ligand and 2) formation of a quaternary carbon center, which have been hitherto unknown for olefin hydroarylation through chelation-assisted CÀH activation.Our study began with intramolecular cyclization of indole 1 a bearing an aldimine moiety on the C3 position and a homoallyl group on the N atom (Table 1). In light of our recent study on cobalt-catalyzed, chelation-assisted intermolecular olefin hydroarylation, [10,11] screening of reaction conditions was performed using 10 mol % of CoBr 2 , 10-20 mol % Figure 1. Biologically active compounds containing dihydropyrroloindole or tetrahydropyridoindole moieties. Scheme 1. Intramolecular hydroarylation leading to dihydropyrroloindole and tetrahyd...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Cobalt‐Catalyzed Intramolecular Olefin Hydroarylation Leading to Dihydropyrroloindoles and Tetrahydropyridoindoles

2013

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“…BesideR h, other catalytic systems involving Ir, [7] Ru, [8] and Pd [9] compounds have also been studied. More recently,Maiti et al [10] have used Pd(OAc) 2 for the decarbonylation of aldehydes.T he major drawback of these reactions is the loss of ac arbon atom during the transformations, which makes them less atom efficient. To attain better atom efficiency,atwo-step approach involving reductiono ft he aldehyde followed by hydrodeoxygenation [11] was employed.…”

Section: Introductionmentioning

confidence: 99%

Palladium Supported on Nanodiamonds as an Efficient Catalyst for the Hydrogenating Deamination of Benzonitrile and Related Compounds

et al. 2016

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Palladium nanoparticles were successfully prepared on a nanodiamond (ND) support and used for the hydrogenating deamination of benzonitrile, aromatic imines, and amines for the first time. The developed methodology was further used for the in situ conversion of aldehydes into hydrocarbons, including a biomass‐derived model compound. The activity of the catalyst was compared with palladium supported on activated carbon (AC) under identical conditions and the performance of Pd/ND was found to be superior to Pd/AC. The origin of the difference in the catalytic performance was considered. Finally, an attempt has been made to understand the mechanism through the identification of the side products by GCMS analysis.

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“…[299] Industrially,furan can be manufactured by the catalytic decarbonylation of furfural (Scheme 1). [300][301][302] According to the literature,palladium has the highest activity, for example,i nl iquid-phase decarbonylation (up to 100 % yield), [303] whereas rhodium, ruthenium, platinum, and nickel demonstrate lower activity. [304] Another approach to the synthesis of furan is the catalytic oxidation of 1,3-butadiene (Scheme 2).…”

Section: Furanmentioning

confidence: 99%

Advanced Biofuels and Beyond: Chemistry Solutions for Propulsion and Production

et al. 2017

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Sustainably produced biofuels, especially when they are derived from lignocellulosic biomass, are being discussed intensively for future ground transportation. Traditionally, research activities focus on the synthesis process, while leaving their combustion properties to be evaluated by a different community. This Review adopts an integrative view of engine combustion and fuel synthesis, focusing on chemical aspects as the common denominator. It will be demonstrated that a fundamental understanding of the combustion process can be instrumental to derive design criteria for the molecular structure of fuel candidates, which can then be targets for the analysis of synthetic pathways and the development of catalytic production routes. With such an integrative approach to fuel design, it will be possible to improve systematically the entire system, spanning biomass feedstock, conversion process, fuel, engine, and pollutants with a view to improve the carbon footprint, increase efficiency, and reduce emissions.

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A general and efficient aldehyde decarbonylation reaction by using a palladium catalyst

Abstract: A facile decarbonylation reaction of aldehydes has been developed by employing Pd(OAc)(2). A wide variety of substrates are decarbonylated, without using any exogenous ligand for palladium as well as CO-scavenger.

Cited by 175 publications

References 32 publications

Cobalt‐Catalyzed Intramolecular Olefin Hydroarylation Leading to Dihydropyrroloindoles and Tetrahydropyridoindoles

Cobalt‐Catalyzed Intramolecular Olefin Hydroarylation Leading to Dihydropyrroloindoles and Tetrahydropyridoindoles

Palladium Supported on Nanodiamonds as an Efficient Catalyst for the Hydrogenating Deamination of Benzonitrile and Related Compounds

Advanced Biofuels and Beyond: Chemistry Solutions for Propulsion and Production

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