Copper-Catalyzed Ring-Opening/Reconstruction of Anthranils with Oxo-Compounds: Synthesis of Quinoline Derivatives

Abstract

A copper-catalyzed protocol for the construction of various 2-aryl­(alkyl)-3-acylquinolines or 3-arylquinolines using readily available anthranils and 1,3-diketones or aldehydes as starting materials is reported herein. Dioxygen as the sole oxidant and hexafluoroisopropanol as the solvent play an important role in both procedures. This ring-opening/reconstruction strategy involving N–O bond cleavage and C–N/C–C bond formation features high yields and broad substrate scope.

A Domino Heck Coupling–Cyclization–Dehydrogenative Strategy for the One-Pot Synthesis of Quinolines

“…Consequently, extensive research efforts have been devoted to accomplishing the synthesis of quinolines and their analogs. [28][29][30][31][32][33][34][35] Over the past three decades, palladium has been utilized as a pre-catalyst for homogenous/heterogeneous catalysis in promoting numerous organic transformations. [36][37][38][39][40][41][42][43] Particularly, in Heck coupling reactions, palladium is an active catalyst when aryl iodides/bromides are used as synthetic precursors in couplings with various alkene partners.…”

Copper-Catalyzed Annulation or Homocoupling of Sulfoxonium Ylides: Synthesis of 2,3-Diaroylquinolines or α,α,β-Tricarbonyl Sulfoxonium Ylides

“…As part of our ongoing interest in the synthesis of heterocycles, , we report our findings on copper-catalyzed synthesis of 2,3-diaroylquinolines through [4+1+1] annulation of sulfoxonium ylides and anthranils (Scheme c, right) . Moreover, an efficient protocol for the synthesis of α,α,β-tricarbonyl sulfoxonium ylides is also presented (Scheme c, left).…”

“…In particular, copper catalysis has now emerged as one of the most ideal catalytic approaches for the synthesis of a variety of value-added bulk and fine chemicals due to the relatively low price and rich reserves . In this regard, our group has recently developed a copper-catalyzed oxidative method for the preparation of quinolines starting from anthranils and oxo-compounds . Quinolines and their derivatives represent a class of significant heterocyclic compounds that are widely found in natural products, drugs, useful ligands, and functional materials .…”

Anthranils: versatile building blocks in the construction of C–N bonds and N-heterocycles

“…Recently, a copper-catalysed protocol for the synthesis of quinoline derivatives from the readily available anthranils and 1,3-diketones/aldehydes 97 was disclosed by the group of Li (Scheme 38). 45 In this reaction, 2-aminobenzaldehyde proved to be a key intermediate on the basis of control experiments, which was generated from a copper-catalysed N-O bond cleavage procedure. The final quinoline products were obtained through a subsequent Friedlander reaction of 2-aminobenzaldehyde and 1,3-diketones.…”