Potassium‐Zincate‐Catalyzed Benzylic C−H Bond Addition of Diarylmethanes to Styrenes

Liu, Yufeng; Zhai, Dan‐Dan; Zhang, Xiangyu; Guan, Bing‐Tao

doi:10.1002/anie.201713165

Cited by 63 publications

(37 citation statements)

References 74 publications

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“…Deuterated xanthenes of type 24 are useful for kinetic as well as mechanistic studies [25] . The KO t Bu‐catalyzed addition of xanthene 3 d to diisopropyl azodicarboxylate provides a novel method for the generation of C−N bond at 9‐position of unsubstituted 9 H ‐xanthene (Scheme 10b) [2a] …”

Section: Resultsmentioning

confidence: 99%

Lewis Acid Catalyzed Reductive Cyclization of 2‐Aryloxybenzaldehydes and 2‐(Arylthio)benzaldehydes to Unsubstituted 9H‐Xanthenes and Thioxanthenes in Diisopropyl Ether

et al. 2020

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Readily accessible 2‐aryloxybenzaldehydes and 2‐(arylthio)benzaldehydes undergo a sequence of reactions leading to a wide variety of unsubstituted 9H‐xanthenes and thioxanthenes in high yields when heated with a Lewis acid in diisopropyl ether. This reductive cyclization method is compatible with several important functional groups. The method is also applicable for the selective reductive cyclization of the more electron‐rich aryl ring of a 2,6‐bis(aryloxy)benzaldehyde. The key feature of this transformation is the chemoselective reduction of a transient xanthylium ion in the presence of aldehydic group via intermolecular hydride transfer from diisopropyl ether (solvent).

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Section: Resultsmentioning

confidence: 99%

Lewis Acid Catalyzed Reductive Cyclization of 2‐Aryloxybenzaldehydes and 2‐(Arylthio)benzaldehydes to Unsubstituted 9H‐Xanthenes and Thioxanthenes in Diisopropyl Ether

et al. 2020

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“…Recently in 2018, Guan and group described a method involving a catalytic amount of potassium zincate complex for benzylic CÀ H bond addition of diarylmethanes to styrenes and conjugated dienes (Scheme 69). [87] The bridging structure of the potassium zincate complex generated from potassium benzyl and zinc amide plays a critical role in the catalytic alkylation reaction thereby showing good activity as well as chemoselectivity. The optimized condition shows a wide substrate scope employing various diarylmethanes as well as differently substituted styrene and dienes.…”

Section: Othersmentioning

confidence: 99%

“…Although many reports, as mentioned above, are available involving base‐catalyzed direct functionalization of the benzylic C−H bond of diarylmethanes, all these methods involve stoichiometric amount of a strong base or an oxidant. Recently in 2018, Guan and group described a method involving a catalytic amount of potassium zincate complex for benzylic C−H bond addition of diarylmethanes to styrenes and conjugated dienes (Scheme ) . The bridging structure of the potassium zincate complex generated from potassium benzyl and zinc amide plays a critical role in the catalytic alkylation reaction thereby showing good activity as well as chemoselectivity.…”

Section: Metal‐free Oxidative Benzylic Cyc‐>h Functionalization Of DImentioning

confidence: 99%

Benzylic Methylene Functionalizations of Diarylmethanes

Gulati

Gandhi

Laha

2020

Chemistry An Asian Journal

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Diarylmethanes are cardinal scaffolds by virtue of their unique structural feature including the presence of a benzylic CH 2 group that can be easily functionalized to generate a variety of fascinating molecules holding immense importance in pharmaceutical, agrochemical, and material sciences. While the originally developed protocols for benzylic CÀ H functionalization in diarylmethanes employing base-mediated and metal-catalyzed strategies are still actively used, they are joined by a new array of metal-free conditions, offering milder and benign conditions. With the recent surge of interest towards the synthesis of functionalized diarylmethanes, numerous choices are now available for a synthetic organic chemist to transform the benzylic CÀ H bond to CÀ C or CÀ X bond offering the synthesis of any molecule of choice. This review highlights benzylic methylene (CH 2) functionalizations of diaryl/heteroarylmethanes utilizing various base-mediated, transition-metal-catalyzed, and transition-metal free approaches for the synthesis of structurally diverse important organic molecules, often with a high chemo-, regio-and enantio-selectivity. This review also attempts to provide analysis of the scope and limitations, mechanistic understanding, and sustainability of the transformations.

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“…Partnering K and Zn within a zincate framework can also give special results, as for example leading to synergic sedation of sensitive anions such as vinyl arising from deprotonation of ethene [5a] . Such potassium‐zinc cooperativity has also been recently extended to the catalytic regime [5b,c] . Among our contributions to this area, recently we investigated the synthesis of sodium magnesiates and zincates based on the bulky silyl(bis)amide ligand {Ph 2 Si(NAr*) 2 } 2− (Ar*=2,6‐diisopropylphenyl) [6,7] .…”

Section: Introductionmentioning

confidence: 99%

Exploiting Deprotonative Co‐complexation to Access Potassium Metal(ates) Supported by a Bulky Silyl(bis)amide Ligand

2021

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Bimetallic complexes combining an alkali‐metal with a lower electropositive metal have demonstrated unique chemical profiles which can be rationalised in terms of chemical cooperativity. Advancing the rational design of these types of complexes, a adaptable method is described to prepare a new family of potassium metal(ates) containing the highly sterically demanding silyl(bis)amide {Ph2Si(NAr*)2}2− (Ar*=2,6‐diisopropylphenyl). Using a sequential deprotonative co‐complexation approach, mono‐metallation of Ph2Si(NHAr*)2 (1) is accomplished using potassium alkyl KCH2SiMe3 yielding [{Ph2Si(NHAr*)(NAr*)K}∞] (2), which, in turn, undergoes co‐complexation with the relevant M(CH2SiMe3)2 (M=Mg, Zn, Mn) enabling metallation of the remaining NHAr* group to furnish silylbis(amido) alkyl potassium metal(ates) [{Ph2Si(NAr*)2M(THF)x(CH2SiMe3)}−{K(THF)y}+] (M=Zn, x=0, y=4, 3; M=Mg, x=1, y=3, 4; and M=Mn, x=0, y=4, 5). Reactivity studies of potassium manganate 5 with the amine HMDS(H) (HMDS=N[SiMe3]2 revealed the kinetic activation of the remaining alkyl group on Mn furnishing [K(THF)2{Ph2Si(NAr*)2}Mn(HMDS)] (6). The structures of these bimetallic complexes along with that of the potassium precursor 2 have been established by X‐ray crystallographic studies.

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Potassium‐Zincate‐Catalyzed Benzylic C−H Bond Addition of Diarylmethanes to Styrenes

Cited by 63 publications

References 74 publications

Lewis Acid Catalyzed Reductive Cyclization of 2‐Aryloxybenzaldehydes and 2‐(Arylthio)benzaldehydes to Unsubstituted 9H‐Xanthenes and Thioxanthenes in Diisopropyl Ether

Lewis Acid Catalyzed Reductive Cyclization of 2‐Aryloxybenzaldehydes and 2‐(Arylthio)benzaldehydes to Unsubstituted 9H‐Xanthenes and Thioxanthenes in Diisopropyl Ether

Benzylic Methylene Functionalizations of Diarylmethanes

Exploiting Deprotonative Co‐complexation to Access Potassium Metal(ates) Supported by a Bulky Silyl(bis)amide Ligand

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