Formal Lossen Rearrangement/[3+2] Annulation Cascade Catalyzed by a Modified Cyclopentadienyl Rh<sup>III</sup> Complex

Yamada, Takayuki; Shibata, Yu; Kawauchi, Susumu; Yoshizaki, Soichi; Tanaka, Ken

doi:10.1002/chem.201801125

Cited by 42 publications

(23 citation statements)

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“…Among secondary and primary carbamoyl groups tested, Cp A1 that possesses the highly acidic N−H group showed the highest catalytic activity (entry 1). Among the tertiary carbamoyl groups that were the effective catalysts for the formal Lossen rearrangement/[3+2] annulation of N ‐pivaloyl benzamides with alkynes, increasing the coordination ability increased the catalytic activity (entry 4 vs. 5), while the product yield did not exceed that using the Cp A1 ligand (entry 1). A newly synthesized Cp A6 Rh III complex bearing a less coordinating N , N ‐diphenylcarbamoyl group, which was prepared via the previously reported [2+2+1] cycloaddition of 1,6‐diyne 4 a with cyclopropylideneacetamide 5 a giving fulvenes 6 aa (Scheme ) followed by its reductive complexation with RhCl 3 (Scheme ), indeed decreased the yield of 3 aa (entry 6).…”

Section: Resultsmentioning

confidence: 99%

Oxidative Annulation of Acetanilides with Alkynes Catalyzed by Cyclopentadienyl Rhodium(III) Complexes with Pendant Amides

et al. 2019

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It has been established that a cationic cyclopentadienyl (Cp) rhodium(III) complex with a pendant Nphenylcarbamoyl moiety (Cp A1 Rh III ) showed high catalytic activity towards the oxidative [3 + 2] annulation of acetanilides with internal alkynes to produce substituted indoles. Catalytic activity of the Cp A1 Rh III complex in the reactions of symmetric internal alkynes (diphenylacetylene and 6-dodecyne) was higher than that of the Cp*-rhodium(III) complex and comparable to that of a Cp-rhodium(III) complex with two ethoxycarbonyl groups (Cp E Rh III ). On the other hand, the Cp A1 Rh III complex showed significantly higher catalytic activity than the Cp E Rh III complex in the reactions of unsymmetric internal alkynes (1-phenyl-1-propyne and 1-phenyl-1-hexyne). Additionally, the catalytic activity of the Cp A1 Rh III complex in the oxidative tandem [2 + 2 + 2] annulation-lactamization of acetanilides with two unsymmetric electron-deficient internal alkynes (ethtyl 2-butynoate) was also comparable to that of the Cp E Rh III complex.

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Section: Resultsmentioning

confidence: 99%

Oxidative Annulation of Acetanilides with Alkynes Catalyzed by Cyclopentadienyl Rhodium(III) Complexes with Pendant Amides

et al. 2019

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“…Thus, the couplingo facrylamides with alkynesi nt he presence of Rh catalyst G1 gave pyrroles 97 a using air as the oxidant (Scheme 44). [77] The uniquenesso fn ew catalysts howcased by giving contrast resultsf rom usual [4+ +2] annulation of amides with alkynes (Scheme 40). The proposed mechanism involved CÀHa ctivation I1,a lkyne insertion I2,aformal Lossen rearrangement I3,a nd reductive elimination.…”

Section: Pyrrolesmentioning

confidence: 99%

Reaching Green: Heterocycle Synthesis by Transition Metal‐Catalyzed C−H Functionalization in Sustainable Medium

Santhoshkumar

Cheng

2019

Chemistry A European J

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Catalytic CÀHf unctionalization has emerged as an efficient alternative to traditional coupling reactions. However,s omeo ft hese reactions depend on environmentally harmful solvents, weakening the overall green nature of these methods. As organic processes consume large amount of solvents, the use of less harmful solvents enhance the sustainability of these reactions. Herein, we present an overview of transition metal-catalyzed CÀHf unctionalization reactions for the synthesis of heterocycles in sustainable solvents based on CHEM21 solvent selection guide.[a] Dr.

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“…The incorporation of substituents on the Cp ring allows both electronic and steric perturbation on the Cp metal complexes [49][50][51]. Well-modified Cp ligands have been used to improve the potential catalytic activity and reaction selectivity of transition metal complexes [52][53][54][55][56][57][58][59][60][61]. Thus, a systematic study of the modified Cp-ligated iridium complex should provide significant insight for the development of a more active catalytic system for acceptorless dehydrogenation reactions.…”

Section: Introductionmentioning

confidence: 99%

Effect of a Substituent in Cyclopentadienyl Ligand on Iridium-Catalyzed Acceptorless Dehydrogenation of Alcohols and 2-Methyl-1,2,3,4-tetrahydroquinoline

Jeong¹,

Shimbayashi²,

Fujita³

2019

Catalysts

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New iridium(III)-bipyridonate complexes having cyclopentadienyl ligands with a series of alkyl substituents were synthesized for the purpose of tuning the catalytic activity for acceptorless dehydrogenation reactions. A comparison of the catalytic activity was performed for the reaction of alcoholic substrates such as 1-phenylethanol, 2-octanol, and benzyl alcohol. The 1-t-butyl-2,3,4,5-tetramethylcyclopentadienyl iridium complex exhibited the best performance, which surpassed that of the 1,2,3,4,5-pentamethylcyclopentadienyl (Cp*) iridium catalyst in the dehydrogenation reaction of alcohols. The catalytic activity in the dehydrogenation of 2-methyl-1,2,3,4-tetrahydroquinoline was also examined. The highest efficiency was obtained in the reaction catalyzed by the same t-butyl-substituted cyclopentadienyl iridium complex.

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Formal Lossen Rearrangement/[3+2] Annulation Cascade Catalyzed by a Modified Cyclopentadienyl Rh^III Complex

Cited by 42 publications

References 50 publications

Oxidative Annulation of Acetanilides with Alkynes Catalyzed by Cyclopentadienyl Rhodium(III) Complexes with Pendant Amides

Oxidative Annulation of Acetanilides with Alkynes Catalyzed by Cyclopentadienyl Rhodium(III) Complexes with Pendant Amides

Reaching Green: Heterocycle Synthesis by Transition Metal‐Catalyzed C−H Functionalization in Sustainable Medium

Effect of a Substituent in Cyclopentadienyl Ligand on Iridium-Catalyzed Acceptorless Dehydrogenation of Alcohols and 2-Methyl-1,2,3,4-tetrahydroquinoline

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Formal Lossen Rearrangement/[3+2] Annulation Cascade Catalyzed by a Modified Cyclopentadienyl RhIII Complex

Cited by 42 publications

References 50 publications

Oxidative Annulation of Acetanilides with Alkynes Catalyzed by Cyclopentadienyl Rhodium(III) Complexes with Pendant Amides

Oxidative Annulation of Acetanilides with Alkynes Catalyzed by Cyclopentadienyl Rhodium(III) Complexes with Pendant Amides

Reaching Green: Heterocycle Synthesis by Transition Metal‐Catalyzed C−H Functionalization in Sustainable Medium

Effect of a Substituent in Cyclopentadienyl Ligand on Iridium-Catalyzed Acceptorless Dehydrogenation of Alcohols and 2-Methyl-1,2,3,4-tetrahydroquinoline

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Formal Lossen Rearrangement/[3+2] Annulation Cascade Catalyzed by a Modified Cyclopentadienyl Rh^III Complex