Efficient [Cu(NHC)]‐Catalyzed Multicomponent Synthesis of Pyrroles

Dang, Tuan Thanh; Seayad, Abdul Majeed

doi:10.1002/asia.201701045

Cited by 24 publications

(10 citation statements)

References 64 publications

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“…In recent years, various homogeneous and heterogeneous catalytic methods have emerged in the borrowing hydrogen field. For homogeneous applications, different transition metal catalysts based on iridium, copper, nickel, iron, cobalt, manganese, rhodium and ruthenium have been employed. Especially the ruthenium‐based systems have been widely and successfully applied to a large variety of amines and nitriles…”

Section: Introductionmentioning

confidence: 99%

Ruthenium Catalyzed N‐Alkylation of Cyclic Amines with Primary Alcohols

2020

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A robust alcohol amination protocol using common saturated amines and primary alcohols as starting materials is described. The reactions are catalyzed by combination of dichloro(p-cymene)ruthenium(II) dimer precatalyst with triphenylphosphine ligand, with the excess alcohol substrate or toluene [a] Dr.amines. An important secondary goal was to minimize the waste produced in the purification of the products, i.e., simple removal of catalyst complex and purification of products without the need of chromatographic separation. Here, we describe a robust triphenylphosphine ligated dichloro(p-cymene)ruthenium(II) dimer catalyzed methodology for alkylation of cyclic amines with primary alcohols, while simultaneously minimizing the necessary purification operations. Results and DiscussionThe N-alkylation of morpholine with 1-butanol, illustrated in Scheme 2, was selected as a model reaction, based on the good availability of the reactants. This allowed the reactions to be performed at close to one gram scale in the preliminary screening, carried out in stainless steel reactors at elevated pressure and temperature. Scheme 2. N-Alkylation of morpholine with 1-butanol using dichloro(p-cymene)ruthenium(II) dimer precatalyst in combination with phosphine ligands.Based on prior art, [16][17][18]20] a selection of phosphine ligands illustrated in Figure 2 were tested. Results from the ligand screening are summarized in Table 1. As expected, the bidentate ligands DPPF, DPPB and DPEphos in combination with dichloro(p-cymene)ruthenium(II) dimer provided good results even at 0.13 mol-% catalyst loading within 21 hours (Table 1, Entries 4, 15 and 17). Tridentate Triphos ligand provided acceptable results in the same reaction setting (Table 1, Entry 21). Also, a number of monodentate ligands, cataCXium®PCy, triphenylphosphine (Ph 3 P) and methoxy derivatized triphenylphosphines were investigated. All monodentate ligands resulted in relatively poor GC-based yields for N-butyl morpholine, or in no reaction at all. In cases of bidentate ligands, having excess of ligand to ruthenium center (above 1:1 ratio) had minimal to no benefits with respect to the overall yield of N-butyl Figure 2. Ligands used in the reaction screening.

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Section: Introductionmentioning

confidence: 99%

Ruthenium Catalyzed N‐Alkylation of Cyclic Amines with Primary Alcohols

2020

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“…Ideally, if such a catalyst is also suitable for subsequent cyclization, a proper synthetic will be developed. In 2017, Seayad and co-workers [115] reported a [Cu(NHC)]-catalyzed threecomponent coupling reaction of ketone, primary amine and diol for the syntheses of substituted pyrroles (Scheme 79). However, the regioselectivity of this cyclization for diol substrate was not investigated.…”

Section: Scheme 78 Copper-catalyzed Annulation Of Alkylamines and Aromatic Acetaldehydesmentioning

confidence: 99%

Recent Advances on Pyrrole Synthesis through Different Annulation Modes

Xu¹,

Chen²,

Zhang³

et al. 2021

Chinese Journal of Organic Chemistry

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“…Dang and co‐workers reported three‐component and two‐component reaction methods for the synthesis of 1,2‐, 1,2,3‐, 1,2,3,5‐substituted pyrroles (from ketone, primary amine and diol) and N‐unsubstituted pyrroles (from β‐aminoalcohol and ketone) respectively using an efficient Cu‐NHC catalyst in presence of LiO‐ t‐ Bu (Scheme ) . The optimization studies of the three‐component reaction involved 2‐phenylethanamine, acetophenone and ethylene glycol and revealed the use of in situ generated Cu‐NHC complex from an N‐aliphatic saturated precursor (SIAd) and CuBr in presence of LiO‐ t‐ Bu.…”

Section: Synthesis Of Heterocyclesmentioning

confidence: 99%

Copper‐Catalysed Multicomponent Syntheses of Heterocycles

Cherian¹,

Harry²,

Saranya³

et al. 2019

Asian J Org Chem

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Heterocycles cover a wide range of organic compounds and are ubiquitous in different areas of life sciences and technology. Multicomponent syntheses of heterocycles are very advantageous in comparison with the classical methods of heterocycle synthesis. In this review, copper-catalysed multicomponent reactions used for the synthesis of heterocycles published between 2004 and 2018 are summarised.[a] R. Scheme 1. Synthesis of 2-iminooxetanes and maleimides by Cu-catalysed three-component reaction and ring expansion respectively.

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Efficient [Cu(NHC)]‐Catalyzed Multicomponent Synthesis of Pyrroles

Cited by 24 publications

References 64 publications

Ruthenium Catalyzed N‐Alkylation of Cyclic Amines with Primary Alcohols

Ruthenium Catalyzed N‐Alkylation of Cyclic Amines with Primary Alcohols

Recent Advances on Pyrrole Synthesis through Different Annulation Modes

Copper‐Catalysed Multicomponent Syntheses of Heterocycles

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