Hydroaminomethylation of olefins using a rhodium carbene catalyst

Seayad, Abdul Majeed; Selvakumar, Kumaravel; Ahmed, Moballigh; Beller, Matthias

doi:10.1016/s0040-4039(03)00008-x

Cited by 56 publications

(31 citation statements)

References 18 publications

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“…[14] On the other hand, the same reaction in polar solvents was almost ineffective (entry 7) and the use of RhA C H T U N G T R E N N U N G (cod)A C H T U N G T R E N N U N G (IPr)Cl resulted in reduced yield under the otherwise identical conditions (entry 11). [15] It should be noted that the Rh-NHC species utilized in this study are easily prepared and highly stable to air, and the amide forming-reaction can be carried out under ambient conditions without requiring an inert atmosphere.…”

mentioning

confidence: 99%

Significant Self‐Acceleration Effects of Nitrile Additives in the Rhodium‐Catalyzed Conversion of Aldoximes to Amides: A New Mechanistic Aspect

Kim

Lee

et al. 2009

Adv Synth Catal

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It was found that the catalytic activity of rhodium complexes was highly sensitive to the type of N-heterocyclic carbene (NHC) ligands in the conversion of aldoximes to amides. Among those species examined, the (cyclooctadiene)rhodium chloride-carbene complex RhACl exhibited the highest reactivity when it was employed in combination with a Brønsted acid, thus allowing mild reaction conditions. A significant rate acceleration effect resulting from the addition of nitrile additives was also observed. With the new protocol, the substrate scope of aldoximes has been widely expanded to include sterically congested and electronically varied derivatives. On the basis of detailed mechanistic studies, it is proposed that the reaction proceeds mainly via intramolecular electrophilic addition of aldoxime to rhodium-bound nitrile, which is different from the generally postulated two-step route: dehydration of aldoxime to nitrile followed by hydration of the latter intermediate.

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confidence: 99%

Significant Self‐Acceleration Effects of Nitrile Additives in the Rhodium‐Catalyzed Conversion of Aldoximes to Amides: A New Mechanistic Aspect

Kim

Lee

et al. 2009

Adv Synth Catal

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“…The introduction of the triphenylphosphine ligand in the coordination sphere of rhodium results in the n/iso ratio increase since the hydridic character of the RhÀ H bond is higher and favors the formation of the linear alkyl moiety. Hydroaminomethylation with N-Heterocyclic carbene ligands has first been reported by Beller et al [44,45] Scheme 12. [40] Operating at somewhat higher temperatures (60 to 100 8C) the reaction converted all the styrene and morpholine to reach a selectivity for the branched amine of 85.5 %.…”

Section: Nitrogen-containing Ligandsmentioning

confidence: 97%

Recent Advances in Amine Synthesis by Catalytic Hydroaminomethylation of Alkenes

2011

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Carbon–carbon coupling catalyzed by transition metals represents a powerful synthetic method to have an access to organic molecules, especially when they present a significant complexity. The strategy to transform abundant and not expensive reactants into products of pharmaceutical interest by the appropriate catalytic way is of fundamental interest, provided that high conversion rates and selectivities can be gained. During the past decade, considerable progress has been made to transform a simple alkene into an aldehyde by carbonylation, to condense it with an NH function‐containing molecule present in the medium, and to hydrogenate the resulting imine or enamine into the relevant amine. Rhodium complexes are able to catalyze this series of reactions and be an efficient synthetic tool to produce rather sophisticated amines in one‐pot reactions under mild conditions of pressure and temperature. In the future, the production of various amines required by the industry of fine chemicals looks attractive by means of this catalytic method.

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“…[RhCl(IPr)(cod)] 12 (1) and [RhCl(IMes)(cod)] 13 (2) [cod = 1,5-cyclooctadiene, IPr = 1,3-diisopropylimidazolin-2-ylidene, and IMes = 1,3-dimesitylimidazolin-2-ylidene] ( Figure 1) were prepared by deprotonation of the corresponding imidazolium salt with potassium tertbutoxide followed by transmetalation with [RhCl(cod)] 2 , as already described in the literature. Macrocyclic ligands, cycloisomerized in the group using the Wilkinson catalyst, 14 were the first substrates to be tested.…”

Section: Rhodium N-heterocyclic Carbene Complexes As Effective Catalymentioning

confidence: 99%

“…Furthermore, the corresponding phosphane oxides formed at the end of the process often hamper product purification. Therefore, the aim of the present study was to test the ability of readily available [RhCl(IPr)(cod)] and [RhCl(IMes)(cod)] complexes towards [2+2+2] carbocyclization of macrocyclic triynes and enediynes, as well as in intramolecular and partially intramolecular versions in order to circumvent the drawbacks of phosphane use.[RhCl(IPr)(cod)] 12 (1) and [RhCl(IMes)(cod)] 13 (2) [cod = 1,5-cyclooctadiene, IPr = 1,3-diisopropylimidazolin-2-ylidene, and IMes = 1,3-dimesitylimidazolin-2-ylidene] (Figure 1) were prepared by deprotonation of the corresponding imidazolium salt with potassium tertbutoxide followed by transmetalation with [RhCl(cod)] 2 , as already described in the literature. …”

mentioning

confidence: 99%

Rhodium N-Heterocyclic Carbene Complexes as Effective Catalysts for [2+2+2]-Cycloaddition Reactions

González¹,

Pla‐Quintana²,

Roglans³

2009

Synlett

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Rhodium complexes of N-heterocyclic carbenes (NHC) [RhCl(cod)(NHC)], [cod = 1,5-cyclooctadiene, NHC = 1,3-diisopropylimidazolin-2-ylidene, and NHC = 1,3-dimesitylimidazolin-2-ylidene] are tested for intra-and partially intramolecular [2+2+2]-cycloaddition reactions demonstrating their effectiveness in this kind of process. This is the first use of a rhodium-NHC complex in a [2+2+2]-cycloaddition reaction of three alkynes. ESI-MS has been used to detect oxidative addition intermediates using rhodium NHC as the catalytic system. The development of efficient methods for transitionmetal-catalyzed [2+2+2]-cycloaddition reactions of unsaturated substrates has attracted considerable attention in recent decades. 1 A number of excellent procedures have been published using various transition metals. Among the metals able to promote this atom-economical transformation, rhodium has been widely used due to its efficient performance in catalytic conditions. Phosphane-stabilized rhodium complexes, whether the Wilkinson catalyst or a combination of [Rh(cod) 2 ]BF 4 and bidentate diphosphine ligands (i.e., BINAP), constitute the most common source of rhodium for these transformations. Rhodium complexes stabilized by N-heterocyclic carbene (NHC) ligands show great electronic versatility, are easy to handle, readily synthesized, and have applications in other rhodium-catalyzed transformations (C-H activation, hydroborylation, hydrosililation, etc.). 2 However, they have been little used in cycloaddition reactions, and only a few studies have described the use of Rh-NHC complexes in this kind of process. Evans et al. described a diastereoselective [4+2+2] cycloaddition 3 of 1,6-enynes and 1,3-butadiene, Chung et al. developed [4+2] and [5+2] cycloadditions of dienynes and alkyne vinylcyclopropanes, respectively, in their intra-and intermolecular versions, 4 and Webster and Li used a quinoline-tethered NHC to assist rhodium to catalyze a [3+2] cycloaddition of diphenylcyclopropenone and internal alkynes. 5 The use of transition-metal catalysts of metals other than rhodium stabilized with NHC for [2+2+2]-cycloaddition reactions has also been reported by some groups in the last decade. Louie et al. used Ni-NHC complexes with great success in [2+2+2] cycloadditions of two alkynes and aldehydes and ketones, 6 isocyanates, 7 nitriles, 8 and carbon dioxide. 9 Okamoto et al. described the intramolecular cyclotrimerization of triynes catalyzed by NHC cobalt and iron complexes, 10 and more recently Aubert, Gandon et al. reported a straightforward [2+2+2] cycloaddition of enediynes mediated by cobalt and an N-heterocyclic carbene in the presence of manganese. 11Phosphane ligands, mainly used to stabilize rhodium catalysts in [2+2+2]-cycloaddition reactions, are prone to oxidation and so the reactions need to be run in anaerobic conditions. Furthermore, the corresponding phosphane oxides formed at the end of the process often hamper product purification. Therefore, the aim of the present study was to test the ability of readily available [Rh...

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Hydroaminomethylation of olefins using a rhodium carbene catalyst

Cited by 56 publications

References 18 publications

Significant Self‐Acceleration Effects of Nitrile Additives in the Rhodium‐Catalyzed Conversion of Aldoximes to Amides: A New Mechanistic Aspect

Significant Self‐Acceleration Effects of Nitrile Additives in the Rhodium‐Catalyzed Conversion of Aldoximes to Amides: A New Mechanistic Aspect

Recent Advances in Amine Synthesis by Catalytic Hydroaminomethylation of Alkenes

Rhodium N-Heterocyclic Carbene Complexes as Effective Catalysts for [2+2+2]-Cycloaddition Reactions

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