One-Pot Synthesis of Substituted Benzo[<i>b</i>]furans and Indoles from Dichlorophenols/Dichloroanilines Using a Palladium–Dihydroxyterphenylphosphine Catalyst

Yamaguchi, Miyuki; Akiyama, Tomoyo; Sasou, Hirohisa; Katsumata, Haruka; Manabe, Kei

doi:10.1021/acs.joc.6b00824

Cited by 38 publications

(22 citation statements)

References 92 publications

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“…(Scheme 5). 8 Various 2-substituted benzofurans (16) were prepared from 2-chlorophenols (15) in moderate-to-excellent yields. However, although the use of this catalyst system selectively yielded bromobenzofurans from the corresponding dibromophenols, chlorobenzofuran synthesis from dichlorophenols has not been reported.…”

Section: -1 Synthesis Of Monochlorobenzofurans From Dichlorophenols Via Ortho-selective Sonogashiramentioning

confidence: 99%

Synthesis of Multisubstituted Benzofurans/Indoles Using Multichlorinated Phenols/Anilines via Palladium-Catalyzed Site-Selective Sonogashira Coupling

Manabe¹,

Yamaguchi²

2022

HETEROCYCLES

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Multisubstituted benzofurans/indoles are a critical class of compounds in the fields of pharmaceuticals and natural products. A useful method of preparing 2-substituted benzofurans/indoles is the Pd-catalyzed Sonogashira coupling of 2-halophenols/2-haloanilines and terminal alkynes, followed by cyclization. For the syntheses of multisubstituted benzofurans/indoles, the use of multichlorinated phenols/anilines as coupling partners is powerful because the synthetic steps required are reduced and all dichlorophenol and dichloroaniline positional isomers are commercially available and inexpensive. However, their use in benzofuran/indole synthesis is limited because of their low reactivity compared with those of the corresponding iodo or bromo compounds. Furthermore, site-selective Sonogashira coupling at the 2-position of the multihalogenated phenols/anilines is sterically and electronically challenging. To overcome these problems, dihydroxyterphenylphosphine (DHTP) has been developed as a ligand that enables the highly ortho-selective Sonogashira coupling of 2-chlorophenols/2-chloroanilines with terminal alkynes. Using the Pd-DHTP catalyst, chlorinated benzofurans/indoles are successfully obtained, which are easily converted to other derivatives by substitution of the chloro group. In this review, we summarize this and related studies to demonstrate the utility of this method. CONTENTS 1. Introduction 2. Synthesis of Disubstituted Benzofurans from Dichlorophenols 2-1. Synthesis of Monochlorobenzofurans from Dichlorophenols via ortho-Selective Sonogashira Coupling/Cyclization 2-2. One-Pot Synthesis of Disubstituted Benzofurans via ortho-Selective Sonogashira Coupling/Cyclization/Suzuki-Miyaura Coupling 3. Synthesis of Multisubstituted Benzofurans from Dichlorophenols via ortho-Selective Sonogashira Coupling/Cacchi Cyclization 4. Synthesis of Multisubstituted Indoles from Multichlorinated Anilines 4-1. Synthesis of Multisubstituted Indoles from Dichloroanilines via ortho-Selective Sonogashira Coupling/Cyclization 4-2. One-Pot Synthesis of Multisubstituted Indoles from Dichloroanilines via ortho-Selective Sonogashira Coupling/Cyclization/Suzuki-Miyaura Coupling 4-3. Synthesis of 2,5,7-Trisubstituted Indoles from 2,4,6-Trichloroaniline 5. Conclusion

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Section: -1 Synthesis Of Monochlorobenzofurans From Dichlorophenols Via Ortho-selective Sonogashiramentioning

confidence: 99%

Synthesis of Multisubstituted Benzofurans/Indoles Using Multichlorinated Phenols/Anilines via Palladium-Catalyzed Site-Selective Sonogashira Coupling

Manabe¹,

Yamaguchi²

2022

HETEROCYCLES

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“…Well recognized tandem alkynylation/cyclization reactions of terminal alkynes with o‐hydroxy aryl halides to form benzofurans is generally carried out using a palladium catalyst along with a copper salt as a co‐catalyst . Nevertheless, the literature comprises Cu‐free Sonogashira alkynylation and synchronous methodologies of cyclization, Balakrishna and co‐workers carried out tandem Cu–Free Sonogashira alkynylation/cyclization reactions of 2‐iodophenol and substituted alkynes using palladium complex 11‐Pd and achieved up to 99 % conversion with a catalyst loading of 1 mol‐% as shown in Scheme .…”

Section: Reviews On Triazole‐based Phosphine Chemistrymentioning

confidence: 99%

Triazole Appended Phosphines: Synthesis, Palladium Complexes, and Catalytic Studies

Mondal

Balakrishna

2020

Eur J Inorg Chem

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The copper(I)-catalyzed triazole formation from azides and terminal alkynes has received the benchmark of "click chemistry" because of its dependability and explicitness. The extensive utility of click chemistry in all aspects from making classical phosphine ligands, investigating its reactivity in serving as an effective catalyst for various organic transformations is well documented. Therefore, designing a decent ligand system with adequate nature and vast diversity is vital for having [a

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“…The reaction reported in Table 1 entry 2 was then applied to the total synthesis of other derivatives, among them the bisindole natural product (−)-aspergilazine A (Scheme 33) [61]. In the reaction reported in Table 1 entry 1 [60], the N-tosyl protecting group was found essential to obtain good results, but no explanation was given. The reaction is highly ortho-selective, in fact, only the ortho-chloro substituent underwent coupling in dichloroanilines, also in the presence of an excess amount of alkyne.…”

Section: -Haloaniline Alkyne Reaction Conditions Indole Yields (%) Refmentioning

confidence: 99%

Recent Progress in the Transition Metal Catalyzed Synthesis of Indoles

Mancuso

Dalpozzo

2018

Catalysts

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Indole is the most frequently found heterocyclic core structures in pharmaceuticals, natural products, agrochemicals, dyes and fragrances. For about 150 years, chemists were absorbed in finding new and easier synthetic strategies to build this nucleus. Many books and reviews have been written, but the number of new syntheses that appear in the literature, make necessary continuous updates. This reviews aims to give a comprehensive overview on indole synthesis catalyzed by transition metals appeared in the literature in the years 2016 and 2017.

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One-Pot Synthesis of Substituted Benzo[b]furans and Indoles from Dichlorophenols/Dichloroanilines Using a Palladium–Dihydroxyterphenylphosphine Catalyst

Cited by 38 publications

References 92 publications

Synthesis of Multisubstituted Benzofurans/Indoles Using Multichlorinated Phenols/Anilines via Palladium-Catalyzed Site-Selective Sonogashira Coupling

Synthesis of Multisubstituted Benzofurans/Indoles Using Multichlorinated Phenols/Anilines via Palladium-Catalyzed Site-Selective Sonogashira Coupling

Triazole Appended Phosphines: Synthesis, Palladium Complexes, and Catalytic Studies

Recent Progress in the Transition Metal Catalyzed Synthesis of Indoles

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