Rhodium(II)‐Catalyzed Cyclization of Bis(<i>N</i>‐tosylhydrazone)s: An Efficient Approach towards Polycyclic Aromatic Compounds

Xia, Ying; Liu, Zhenxing; Xiao, Qing; Qu, Peiyuan; Ge, Rui; Zhang, Yan; Wang, Jianbo

doi:10.1002/anie.201201374

Cited by 145 publications

(75 citation statements)

References 76 publications

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“…All the cobalt-porphyrin catalysts [Co II ( P1 )], [Co II ( P2 )] [Co II ( P3 )], and N tosylhydrazone sodium salts were synthesized according to published procedures. 7a,8,11 All the alkynes were used as purchased from Aldrich. All other chemicals were purchased from commercial suppliers and used without further purification.…”

Section: Methodsmentioning

confidence: 99%

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Metalloradical Approach to 2H-Chromenes

et al. 2014

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Cobalt(III)–carbene radicals, generated through metalloradical activation of salicyl N-tosylhydrazones by cobalt(II) complexes of porphyrins, readily undergo radical addition to terminal alkynes to produce salicyl-vinyl radical intermediates. Subsequent hydrogen atom transfer (HAT) from the hydroxy group of the salicyl-moiety to the vinyl-radical leads to the formation of 2H-chromenes. The Co(II)-catalyzed process can tolerate various substitution patterns and produces the corresponding 2H-chromene products in good isolated yields. EPR spectroscopy and radical-trapping experiments with TEMPO are in agreement with the proposed radical mechanism. DFT calculations reveal the formation of the salicyl-vinyl radical intermediate by a metalloradical mediated process. Unexpectedly, subsequent HAT from the hydroxy moiety to the vinyl radical leads to formation of an o-quinone methide intermediate, which dissociates spontaneously from the cobalt center and easily undergoes an endo-cyclic, sigmatropic ring-closing reaction to form the final 2H-chromene product.

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Section: Methodsmentioning

confidence: 99%

“…10 The use of N -tosylhydrazones 11 as diazo precursors in [Co(Por)]-based metalloradical catalysis was thus far unprecedented, which may open up a new area to bring about new chemical transformations using in-situ generated unstable diazo-precursors that are otherwise difficult to handle. 11 …”

Section: Introductionmentioning

confidence: 99%

Metalloradical Approach to 2H-Chromenes

et al. 2014

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“…Complementary approaches have been developed to overcome these challenges that are based on Diels-Alder cycloaddition reactions, 13 radical cyclizations, 14 and metal-mediated cycloisomerizations. 15 Additionally, rhodium-and ruthenium-catalyzed procedures have been reported that rely on bis(N-tosylhydrazone) 16 2 as substrate (Fig. 1A I) and olefin-metathesis reactions of bis(alkenes) 17 4 (Fig.…”

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confidence: 99%

Polycyclic Aromatic Hydrocarbons via Iron(III)-Catalyzed Carbonyl–Olefin Metathesis

2017

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Polycyclic aromatic hydrocarbons are important structural motifs in organic chemistry, pharmaceutical chemistry and materials science. The development of a new synthetic strategy toward these compounds is described based on the design principle of iron(III)-catalyzed carbonyl-olefin metathesis reactions. This approach is characterized by its operational simplicity, high functional group compatibility, and regioselectivity while relying on FeCl3 as an environmentally benign, earth-abundant metal catalyst. Experimental evidence for oxetanes as reactive intermediates in the catalytic carbonyl-olefin ring-closing metathesis has been obtained.

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“…In his approach bis(N-tosylhydrazone)s were cyclized using an Rh-catalyst [93]. The starting materials are easily accessible via Suzuki cross-coupling reaction (Scheme 37).…”

Section: Transition Metal Mediated Cyclizationsmentioning

confidence: 99%

Strategies in Organic Synthesis for Condensed Arenes, Coronene, and Graphene

Tran‐Van

Wegner

2013

Polyarenes I

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Graphene-type structures are without doubt one of the most exciting carbon-based materials known. Although graphene is mostly prepared by physical methods (CVD, exfoliation), organic synthesis represents a powerful alternative to access graphene-type structures in a selective and reproducible manner. Although graphene has been hyped as a "new" material, the resemblance to polycyclic aromatic hydrocarbons (PAHs) offers a long history in organic chemistry on which all new endeavors are built. In this review we demonstrate the state-of-the-art of organic synthetic strategies for the preparation of graphene-type structures on selected examples.

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Rhodium(II)‐Catalyzed Cyclization of Bis(N‐tosylhydrazone)s: An Efficient Approach towards Polycyclic Aromatic Compounds

Abstract: Ahead of the PAC: Polycyclic aromatic compounds (PACs) can be easily accessed by the combination of Suzuki–Miyaura cross‐coupling and a [Rh2(OAc)4]‐catalyzed carbene reaction using easily available bis(N‐tosylhydrazone)s as intermediates (see scheme; Ts=4‐toluenesulfonyl).

Cited by 145 publications

References 76 publications

Metalloradical Approach to 2H-Chromenes

Metalloradical Approach to 2H-Chromenes

Polycyclic Aromatic Hydrocarbons via Iron(III)-Catalyzed Carbonyl–Olefin Metathesis

Strategies in Organic Synthesis for Condensed Arenes, Coronene, and Graphene

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