One‐Pot Multicomponent Synthesis of Azaindoles and Pyrroles from One Molecule of a Silicon‐Tethered Diyne and Three or Two Molecules of Organonitriles Mediated by Zirconocene

Zhang, Shaoguang; Sun, Xiaohua; Zhang, Wen‐Xiong; Xi, Zhenfeng

doi:10.1002/chem.200902411

Cited by 30 publications

(9 citation statements)

References 118 publications

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“…Other nitriles with appropriate hindrance, such as 2-methylbutyronitrile could be also applied to stop the reaction in the middle way. 13 The bulkier 1-cyano-1-phenylcyclopropane was utilized in the reaction to afford the sole pyrrole 4c. These pyrroles having four different substituents are difficult to access by other methods.…”

Section: Reaction Of Complex 2 With Nitriles (Class I) Mechanistic As...mentioning

confidence: 99%

“…A wide range of the second nitrile (R 3 CN), for example, aromatic and aliphatic ones, could be applied. 13 In these cases, the reaction generated the 5-azaindoles 3 with the same substituents (R 1 ) at positions 2,4 and a different substituent (R 3 ) at position 6. This reaction not only provides a synthetic method for pyrroles with all different substituents and 5-azaindoles with a different substitution pattern but also provides information on the reaction mechanism.…”

Section: Reaction Of Complex 2 With Nitriles (Class I) Mechanistic As...mentioning

confidence: 99%

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Zirconocene and Si-Tethered Diynes: A Happy Match Directed toward Organometallic Chemistry and Organic Synthesis

Zhang

2011

Acc. Chem. Res.

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Characterizing reactive organometallic intermediates is critical for understanding the mechanistic aspects of metal-mediated organic reactions. Moreover, the isolation of reactive organometallic intermediates can often result in the ability to design new synthetic methods. In this Account, we outline synthetic methods that we developed for a variety of diverse Zr/Si organo-bimetallic compounds and Si/N heteroatom-organic compounds through the detailed study of zirconacyclobutene-silacyclobutene fused compounds. Two basic components are involved in this chemistry. The first is the Si-tethered diyne, which owes its rich reactive palette to the combination of the Si-C bond and the C≡C triple bond. The second is the low-valent zirconocene species Cp(2)Zr(II), which has proven very useful in organic synthesis. The reaction of these two components affords the zirconacyclobutene-silacyclobutene fused compound, which is the key reactive Zr/Si organo-bimetallic intermediate discussed here. We discuss the three types of reactions that have been developed for the zirconacyclobutene-silacyclobutene fused intermediate. The reaction with nitriles (the C≡N triple bond) is introduced in the first section. In this one-pot reaction, up to four different components can be combined: the Si-tethered diyne can be reacted with three identical nitriles, with differing nitriles, or with a nitrile and other unsaturated organic substrates such as formamides, isocyanides, acid chlorides, aldehydes, carbodiimides, and azides. Several unexpected multiring, fused Zr/Si organo-bimetallic intermediates were isolated and characterized. A wide variety of N-heterocycles, such as 5-azaindole, pyrrole, and pyrroloazepine derivatives, were obtained. We then discuss the reaction with alkynes (the C≡C triple bond). A consecutive skeletal rearrangement, differing from that observed in the reactions with nitriles, takes place in this reaction. Finally, we discuss the reaction with the C═X substrates (where X is O or N), including ketones, aldehydes, and isocyanides. Oxa- and azazirconacycles are formed via a new skeletal rearrangement. Our results show that the zirconocene and the Si-tethered diyne cooperate as a "chemical transformer" after treatment with various substrates, leading to a diverse range of cyclic Zr/Si organo-bimetallic compounds. This mechanism-derived synthesis of organometallic and organic compounds demonstrates that the investigation of metal-mediated reactions and the isolation of reactive organometallic intermediates not only contribute to the understanding of complex reactions but can also lead to the discovery of synthetically useful methods.

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Section: Reaction Of Complex 2 With Nitriles (Class I) Mechanistic As...mentioning

confidence: 99%

Section: Reaction Of Complex 2 With Nitriles (Class I) Mechanistic As...mentioning

confidence: 99%

Zirconocene and Si-Tethered Diynes: A Happy Match Directed toward Organometallic Chemistry and Organic Synthesis

Zhang

2011

Acc. Chem. Res.

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“…88 In a related procedure, the zircocene-mediated reaction between bis(arylalkynyl)silanes and nitriles was found to yield pyrroles in moderate yields (Scheme 59). 89…”

Section: Methods Based On Nucleophilic Additions Onto Nitrile Groupsmentioning

confidence: 99%

Multicomponent reactions for the synthesis of pyrroles

2010

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“…Micro elemental analyses were performed on a MICRO CORDER JM10 apparatus. Compounds 2 were prepared and isolated by following our reported procedure 15a. b…”

Section: Methodsmentioning

confidence: 99%

Efficient One‐Pot Synthesis of N‐Containing Heterocycles by Multicomponent Coupling of Silicon‐Tethered Diynes, Nitriles, and Isocyanides through Intramolecular Cyclization of IminoacylZr Intermediates

Zhang

2010

Chemistry A European J

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An efficient multicomponent synthesis of 5-azaindoles and dihydropyrrolo[3,2-c]azepines was achieved by zirconocene-mediated coupling of silicon-tethered diynes, nitriles, and isocyanides. The synthesis, structures, and intramolecular cyclization of mono- and bis(iminoacyl)--Zr intermediates were investigated to elucidate the reaction process. Upon hydrolysis, the isolated mono(iminoacyl)--Zr intermediates underwent intramolecular cyclization to afford tetrasubstituted 5-azaindoles, whereas intramolecular cyclization of bis(iminoacyl)--Zr intermediates led to the formation of dihydropyrrolo[3,2-c]azepines. The structure of a bis(iminoacyl)--Zr intermediate, formed through insertion of two molecules of CyNC into the Zr--C bond, and structures of two dihydropyrrolo[3,2-c]azepines were characterized by single-crystal X-ray structural analysis.

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One‐Pot Multicomponent Synthesis of Azaindoles and Pyrroles from One Molecule of a Silicon‐Tethered Diyne and Three or Two Molecules of Organonitriles Mediated by Zirconocene

Cited by 30 publications

References 118 publications

Zirconocene and Si-Tethered Diynes: A Happy Match Directed toward Organometallic Chemistry and Organic Synthesis

Zirconocene and Si-Tethered Diynes: A Happy Match Directed toward Organometallic Chemistry and Organic Synthesis

Multicomponent reactions for the synthesis of pyrroles

Efficient One‐Pot Synthesis of N‐Containing Heterocycles by Multicomponent Coupling of Silicon‐Tethered Diynes, Nitriles, and Isocyanides through Intramolecular Cyclization of IminoacylZr Intermediates

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