Iodine-Catalyzed Nazarov Cyclizations

Koenig, Jonas J.; Arndt, Thiemo; Gildemeister, Nora; Neudörfl, Jörg‐M.; Breugst, Martin

doi:10.1021/acs.joc.9b01083

Cited by 35 publications

(30 citation statements)

References 88 publications

(99 reference statements)

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“…Consequently, we investigated the influence of iodine on several Diels‐Alder reactions at the B2PLYP‐D3BJ/aug‐cc‐pVTZ/SMD//M06‐2X/6‐311+G(d,p)/SMD level of theory. This method turned out to provide very reliable results for iodine‐catalyzed Michael additions [11a] and Nazarov cyclizations [12] …”

Section: Resultsmentioning

confidence: 99%

“…[10] We were recently able to show that a halogen-bond activation is the most likely explanation for iodine-catalyzed Michael additions [11] and Nazarov cyclizations (Scheme 1). [12] In contrast, a iodonium-activation seems to be the origin for carbonyl-olefin metathesis reactions. [13] As iodine is frequently comparable or even superior in activity compared to traditional metal catalysts like AlCl 3 , FeCl 3 , or TiCl 4 , [11][12][13] we wondered whether this simple catalyst can also be employed in other transformations and affords the desired products under mild conditions.…”

Section: Introductionmentioning

confidence: 99%

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Iodine‐Catalyzed Diels‐Alder Reactions

et al. 2021

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The Diels‐Alder cycloaddition is the most popular pericyclic reaction with numerous applications in synthesis and catalysis. We now demonstrate that we can perform this reaction under mild and metal‐free conditions relying on molecular iodine as the catalyst. Cycloadditions with cyclohexadiene, cyclopentadiene, or isoprene with various dienophiles can be performed typically within minutes in moderate to good yields and high endo selectivity. The mechanistic studies including kinetic and DFT investigations clearly indicate a halogen‐bond activation and rule out other modes of activation. Furthermore, iodine performs equally well as typical metallic Lewis acids like AlCl3, SnCl4, or TiCl4.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Iodine‐Catalyzed Diels‐Alder Reactions

et al. 2021

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Section: -Catalyzed Iso-nazarov Cyclization Of Conjugated Dienalsmentioning

confidence: 99%

“…The XB-catalyzed Nazarov cyclization attracted much attention recently [54,83,84]. Breugst and co-workers reported a combined experimental and computational study of I 2 -catalyzed Nazarov cyclization [84]. Based on their results of kinetic studies, i.e., the reaction being first order in I 2 , and the reaction barrier, as well as comparative control studies, the authors could rule out the Brønsted acid pathway in favor of the XB pathway.…”

Section: -Catalyzed Iso-nazarov Cyclization Of Conjugated Dienalsmentioning

confidence: 99%

Application of Halogen Bonding to Organocatalysis: A Theoretical Perspective

Hui

Wong

2020

Molecules

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The strong, specific, and directional halogen bond (XB) is an ideal supramolecular synthon in crystal engineering, as well as rational catalyst and drug design. These attributes attracted strong growing interest in halogen bonding in the past decade and led to a wide range of applications in materials, biological, and catalysis applications. Recently, various research groups exploited the XB mode of activation in designing halogen-based Lewis acids in effecting organic transformation, and there is continual growth in this promising area. In addition to the rapid advancements in methodology development, computational investigations are well suited for mechanistic understanding, rational XB catalyst design, and the study of intermediates that are unstable when observed experimentally. In this review, we highlight recent computational studies of XB organocatalytic reactions, which provide valuable insights into the XB mode of activation, competing reaction pathways, effects of solvent and counterions, and design of novel XB catalysts.

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“…The reactions directed towards synthesizing imidazole derivatives in the absence of metal catalysts are rare . Contemporaneously, direct oxidative C−H functionalization using iodine as a catalyst got considerable attention and provided an excellent avenue to form various heterocycles using readily available raw materials . Iodine‐catalyzed reactions are less expensive, environmentally benign, and known to be chemoselective.…”

Section: Introductionmentioning

confidence: 99%

Iodine‐Catalyzed C−H Functionalization of Cyclopentenedione with Benzamidine: A Double Dehydrogenative Oxidative Cyclization to Access Fused Imidazoles

2020

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A double C−H functionalization of cyclopentenedione with benzamidine hydrochloride catalyzed by iodine has been disclosed for synthesizing fused imidazole derivatives. This methodology leads to a variety of fused imidazole derivatives and requires a sub‐stoichiometric amount of iodine as a catalyst and aqueous tert‐butyl hydroperoxide (TBHP) as an oxidant. This reaction involves a double‐cross dehydrogenative coupling (CDC) of 1,3‐cyclopentenedione and benzamidine hydrochloride to form two C−N bonds in a consecutive manner within short reaction time. A plausible mechanism has been proposed based on the mass spectrometric analysis.

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Iodine-Catalyzed Nazarov Cyclizations

Cited by 35 publications

References 88 publications

Iodine‐Catalyzed Diels‐Alder Reactions

Iodine‐Catalyzed Diels‐Alder Reactions

Application of Halogen Bonding to Organocatalysis: A Theoretical Perspective

Iodine‐Catalyzed C−H Functionalization of Cyclopentenedione with Benzamidine: A Double Dehydrogenative Oxidative Cyclization to Access Fused Imidazoles

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