Metal‐Free <i>meta</i>‐Selective Alkyne Oxyarylation with Pyridine <i>N</i>‐Oxides: Rapid Assembly of Metyrapone Analogues

Chen, Xiangyu; Ruider, Stefan A.; Hartmann, Rolf W.; González, Leticia; Maulide, Nuno

doi:10.1002/anie.201607988

Cited by 36 publications

(23 citation statements)

References 63 publications

(19 reference statements)

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“…Other examples comprise cycloaddition reactions of ynones, diynes and enynones with quinoline and isoquinoline N ‐oxides, and meta ‐selective alkyne oxyarylation with pyridine N ‐oxides …”

Section: Oxygenation Of Unsaturated Bondsmentioning

confidence: 99%

Heteroarene N‐Oxides as Oxygen Source in Organic Reactions

2018

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This review summarizes the utilization of heteroarene N‐oxides as oxidant in organic reactions. The specific focus lies on reactions in which pyridine N‐oxides are used as oxygen source in an oxygen atom transfer fashion. The scope comprises the hydroxylation of aliphatic and aromatic C–H bonds, epoxidation as well as oxygenations of alkenes and alkynes. The latter have been extensively reviewed elsewhere and are merely discussed in a conceptual manner.

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Section: Oxygenation Of Unsaturated Bondsmentioning

confidence: 99%

Heteroarene N‐Oxides as Oxygen Source in Organic Reactions

2018

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“…We then investigated other non-noble metals (Table 1 , entries 2−6), and were pleased to find that Cu(CH 3 CN) 4 PF 6 catalyzed the oxidative cyclization to produce the desired 2a in 41% yield (Table 1 , entry 6). Of note, rhodium (Table 1 , entry 7) 35 and Brønsted acids 56 – 59 such as TsOH and TfOH were not effective in promoting this reaction (for more details see Supplementary Table 1 ). Interestingly, pyrrolo[2,3- b ]indole 3a was obtained as the main product in the presence of typical gold catalysts such as Ph 3 PAuNTf 2 and IPrAuNTf 2 (Table 1 , entries 8 and 9).…”

Section: Resultsmentioning

confidence: 99%

Divergent synthesis of N-heterocycles via controllable cyclization of azido-diynes catalyzed by copper and gold

et al. 2017

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Gold-catalyzed intermolecular alkyne oxidation by an N–O bond oxidant has proven to be a powerful method in organic synthesis during the past decade, because this approach would enable readily available alkynes as precursors in generating α-oxo gold carbenes. Among those, gold-catalyzed oxidative cyclization of dialkynes has received particular attention as this chemistry offers great potential to build structurally complex cyclic molecules. However, these alkyne oxidations have been mostly limited to noble metal catalysts, and, to our knowledge, non-noble metal-catalyzed reactions such as diyne oxidations have not been reported. Herein, we disclose a copper-catalyzed oxidative diyne cyclization, allowing the facile synthesis of a wide range of valuable pyrrolo[3,4-c]quinolin-1-ones. Interestingly, by employing the same starting materials, the gold-catalyzed cascade cyclization leads to the divergent formation of synthetically useful pyrrolo[2,3-b]indoles. Furthermore, the proposed mechanistic rationale for these cascade reactions is strongly supported by both control experiments and theoretical calculations.

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“…[12] Primary and secondary aniline derivatives are also wellknown to act as ortho-directing groups for metal-catalyzed C À Hf unctionalization (Scheme 1b). [14] Additionally,w ea nd others [15] have observed that the addition of pyridine N-oxides to keteniminium intermediates may lead to the formation of an electrophilic enolonium-like species that is prone to interception by appropriate nucleophiles (Scheme 1c,b ottom reaction). [14] Additionally,w ea nd others [15] have observed that the addition of pyridine N-oxides to keteniminium intermediates may lead to the formation of an electrophilic enolonium-like species that is prone to interception by appropriate nucleophiles (Scheme 1c,b ottom reaction).…”

mentioning

confidence: 99%