Synthesis, Isolation, and Characterization of Mono- and Bis-norbornene-Annulated Biarylamines through Pseudo-Catellani Intermediates

Annamalai, Pratheepkumar; Hsiao, Huan Chang; Raju, Selvam; Fu, Yi Hsuan; Chen, Pei-Ling; Horng, Jia Cherng; Liu, Yi Hung; Chuang, Shih‐Ching

doi:10.1021/acs.orglett.9b00119

Cited by 13 publications

(4 citation statements)

References 42 publications

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“…Along this line, a variety of aryl sulfonates, including reactive triflates and relatively inactive tosylates and mesylates, were all readily cyclobutanated with strained alkenes by splitting both C–O and C–H bonds, providing an efficient method for preparing benzocyclobutananes. Benzocyclobutananes are building blocks of high value occurring in many functional molecules such as drugs and materials, while their synthesis highly depended on the transformation of organohalides or special aromatics bearing a directing group. ,,− …”

Section: Introductionmentioning

confidence: 99%

Palladium-Catalyzed Cyclobutanation of Aryl Sulfonates through both C–O and C–H Cleavage

et al. 2020

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A palladium-catalyzed cyclobutanation of aryl sulfonates with strained alkenes has been developed. The methodology is featured to achieve the cleavage of both C−O and C−H bonds of phenol derivatives in one pot. Under the reaction conditions, in addition to reactive triflates, the relatively inactive tosylates and mesylates can also be transformed into the corresponding benzocyclobutanes in high yields. This reaction can be carried out in gram-scale experiments with a low loading of the palladium catalyst and is applicable to the cyclobutanative modification of bioactive molecules, highlighting its synthetic value in organic synthesis. ■ RESULTS AND DISCUSSIONAt 100 °C, a mixture of 1-naphthyl triflate (1a) and an alkene (2a, 1.5 equiv) was allowed to react in the presence of 0.5 mol % of Pd 2 (dba) 3 , 2 mol % of PPh 3 , and 2 equiv of K 2 CO 3 at 100

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Section: Introductionmentioning

confidence: 99%

Palladium-Catalyzed Cyclobutanation of Aryl Sulfonates through both C–O and C–H Cleavage

et al. 2020

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“…All the aforementioned Pd-catalyzed transformations are unimolecular reactions producing BCBs via formation of one single C–C bond. , The Pd(0)-catalyzed Catellani reaction allows, on the other hand, the construction of BCBs via concurrent formation of two C–C bonds (Scheme a). Since its initial discovery, this reaction has been examined by several groups. − However, the scope of this annulation reaction remains limited, as only norbornene and its derivatives can be used as the alkene inputs. In connection with our research program dealing with the Pd(II) − and Pd(IV) chemistry, we became interested in developing a modular synthesis of BCBs from alkenes 1 and arylboronic acids 2 .…”

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confidence: 99%

Modular Synthesis of Benzocyclobutenes via Pd(II)-Catalyzed Oxidative [2+2] Annulation of Arylboronic Acids with Alkenes

et al. 2022

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Benzocyclobutenes (BCBs) are highly valuable compounds in organic synthesis, medicinal chemistry, and materials science. However, catalytic modular synthesis of functionalized BCBs from easily accessible starting materials remains limited. We report herein an efficient synthesis of diversely functionalized BCBs by a Pd(II)-catalyzed formal [2+2] annulation between arylboronic acids and alkenes in the presence of N-fluorobenzenesulfonimide (NFSI). An intermolecular carbopalladation followed by palladium oxidation, intramolecular C(sp 2 )−H activation by a transient C(sp 3 )−Pd(IV) species, and selective carbon−carbon (C−C) bond-forming reductive elimination from a high-valent five-membered palladacycle is proposed to account for the reaction outcome. Kinetically competent oxidation of alkylPd(II) to alkylPd(IV) species is important to avoid the formation of a Heck adduct. The reaction forges two C−C bonds of the cyclobutene core and is compatible with a wide range of functional groups. No chelating bidentate directing group in the alkene part is needed for this transformation.

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“…According to our hypothesis regarding the β-C elimination against the second amination as shown in Scheme f, 4-iodoanisole ( 4a ) was tested under the same conditions (in Supporting Information). To our delight, the desired cyclobutane adduct 6aa was obtained in 42% yield with 1,3-diamination/Heck reaction product 7aa in 23% yield . Then ligands and NBE derivates were also investigated to adjust the monoamination/cyclobutanation against diamination (Table ).…”

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confidence: 99%

Palladium/Norbornene Catalyzed ortho Amination/Cyclization of Aryl Iodide: Process to 3-Methyl-indole Derivates and Controllable Reductive Elimination against the Second Amination

Yang

Liu

et al. 2021

Org. Lett.

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A palladium/norbornene cooperative catalyzed selective C−H bond amination of aryl iodides was explored, providing an efficient tool for constructing benzocyclic molecules. When ortho-substituted iodobenzene was involved, the C−H bond amination and following Heck cyclization efficiently delivered a 3-methyl-indole scaffold. On the other hand, we realized the controllable synthesis of monoaminated benzo-cyclobutanyl scaffold. The possible coordination of an installed terminal alkenyl group with palladium and steric hindrance were proposed to be responsible for the monoamination selectivity.

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Synthesis, Isolation, and Characterization of Mono- and Bis-norbornene-Annulated Biarylamines through Pseudo-Catellani Intermediates

Cited by 13 publications

References 42 publications

Palladium-Catalyzed Cyclobutanation of Aryl Sulfonates through both C–O and C–H Cleavage

Palladium-Catalyzed Cyclobutanation of Aryl Sulfonates through both C–O and C–H Cleavage

Modular Synthesis of Benzocyclobutenes via Pd(II)-Catalyzed Oxidative [2+2] Annulation of Arylboronic Acids with Alkenes

Palladium/Norbornene Catalyzed ortho Amination/Cyclization of Aryl Iodide: Process to 3-Methyl-indole Derivates and Controllable Reductive Elimination against the Second Amination

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