Rhodium‐Catalyzed Synthesis of 4‐Bromo‐1,2‐dihydroisoquinolines: Access to Bromonium Ylides by the Intramolecular Reaction of a Benzyl Bromide and an α‐Imino Carbene

Abstract

Highly functionalized 4‐bromo‐1,2‐dihydroisoquinolines were synthesized from readily available 4‐(2‐(bromomethyl)phenyl)‐1‐sulfonyl‐1,2,3‐triazoles. A bromonium ylide is proposed as the key intermediate, which can be formed by the intramolecular nucleophilic attack of the benzyl bromide on the α‐imino rhodium carbene formed in the presence of the rhodium catalyst.

The Divergent Cascade Reactions of Arylalkynols with Homopropargylic Amines or Electron-Deficient Olefins: Access to the Spiro-Isobenzofuran-b-pyrroloquinolines or Bridged-Isobenzofuran Polycycles

“…Synthesis and Characterization of the Arylalkynols (9a− 9f). 12 To a solution of 2-bromobenzaldehyde or its derivatives (20 mmol, 1 equiv), PdCl 2 (PPh 3 ) 2 (702.0 mg, 5 mol %), and CuI (76.0 mg, 2 mol %) in NEt 3 (40.0 mL) was added under N 2 atmosphere. After being stirred for 10 min at room temperature, terminal acetylene (1.5 equiv) was added to the mixture.…”

Recent Advances in the Synthesis of Heterocycles and Related Substances Based on α‐Imino Rhodium Carbene Complexes Derived from N‐Sulfonyl‐1,2,3‐triazoles

“…In 2016, Li and co-workersr eported the rhodium-catalyzed intramolecular reactiono fabenzylb romide and N-sulfonyl triazole (Scheme 40). [54] An intramolecular nucleophilic attack of bromide at the carbene center leads to the formation of bromonium ylide 208,a nd cleavage of one CÀBr bond generatesi ntermediate 209.T he subsequent 6 pelectrocyclic ring closure gives the product 207.…”

Palladium-Catalyzed Synthesis of 3-Haloindol-2-amines from 3-Diazoindolin-2-imines and Alkyl Halides

“…9 A recent work on bromonium ylide formation from rhodium carbene through the rhodium-catalyzed intramolecular reaction of 4-(2-(bromomethyl)phenyl)-1-sulfonyl-1,2,3-triazoles, a class of precursors of α-diazo imines, was reported by Li and coworkers. 10 We previously developed convenient approaches to 3diazoindolin-2-imines 11 and demonstrated that this class of diazo compounds could be utilized as precursors of metal carbenes for a variety of synthetically valuable transformations. 11,12 As a continuation of our studies on diazo compound chemistry and inspired by Li's work, 10 we envisioned that the halonium ylide would be formed from diazoindolin-2-imines and alkyl halides using suitable transition-metal catalysts and that this reactive intermediate would undergo further transformation to provide 3-haloindol-2-amines.…”

“…10 We previously developed convenient approaches to 3diazoindolin-2-imines 11 and demonstrated that this class of diazo compounds could be utilized as precursors of metal carbenes for a variety of synthetically valuable transformations. 11,12 As a continuation of our studies on diazo compound chemistry and inspired by Li's work, 10 we envisioned that the halonium ylide would be formed from diazoindolin-2-imines and alkyl halides using suitable transition-metal catalysts and that this reactive intermediate would undergo further transformation to provide 3-haloindol-2-amines. The halogenated products should be versatile building blocks for the synthesis of 3-functionalized indol-2-amines.…”