Smooth Isoindolinone Formation from Isopropyl Carbamates via Bischler–Napieralski-Type Cyclization

Abstract

Isopropyl carbamates derived from benzylamines provide isoindolinones by treatment with phosphorus pentoxide at room temperature. Utility of this Bischler-Napieralski-type cyclization and a new mechanism involving a carbamoyl cation for rationalization of this smooth conversion are discussed.

Acylative Coupling of Amine and Indole Using Chloroform as a Carbonyl Group

“…2‐Methyl‐3,4‐dihydroisoquinolin‐1(2 H )‐one (10b): Compound 9b (40.6 mg, 0.3 mmol) was dissolved in CHCl 3 (30.0 mL) under air atmosphere. Me 2 Zn (1.0 m in hexane, 2.4 mL, 2.4 mmol) was added to the solution of 9b in CHCl 3 under a nitrogen atmosphere at room temperature.…”

Rh(III)‐Catalyzed Synthesis of Multisubstituted Isoquinolines from Benzylamines and Diazo Compounds

“…Diverse methods have been developed to build this motif. Conventional procedures involve Bischler‐Napieralski,– Pictet‐Spengler– or Pomeranz‐Fritsch– reactions, which suffer from limited availability of the substrates, harsh reaction conditions, in particular requirement of strong Bronsted or Lewis acids. Recently, transition metal‐catalyzed C−H bond functionalization have provided alternative pathway to isoquinolines –.…”

Synthesis of Isoquinolines via Rh(III)‐Catalyzed C−H Annulation of Primary Benzylamines with α‐Cl Ketones

“…[1] Consequently, various synthetic methods have been developed to construct this type of frameworks. Conventional strategies including Pictet-Spengler, [2] Bischler-Napieralski [3] or Pomeranz-Fritsch [4] reactions, have been versatile tools for the isoquinolines synthesis. However, these reactions suffer from harsh reaction conditions, low functional group compatibility and in particular requirement of strong Bronsted or Lewis acids.…”

“…[9] However, among these reactions, the coupling partners were currently limited to the sp-carbon synthons or metal carbine precursors. To the best of our knowledge, sp 3 -carbon synthons as coupling reagents have not been reported in the CÀ H functionalization of benzylamines.…”