Access to Six- and Seven-Membered 1,7-Fused Indolines via Rh(III)-Catalyzed Redox-Neutral C7-Selective C-H Functionalization of Indolines with Alkynes and Alkenes

J Org Chem. 2015 Jun 19;80(12):6238-49. doi: 10.1021/acs.joc.5b00684. Epub 2015 Jun 1.

Abstract

We report herein a new strategy for the Rh(III)-catalyzed redox-neutral C7-selective C-H activation/annulation of indolines to rapidly access various privileged 1,7-fused indolines by utilizing an oxidizing-directing group. For example, a Rh(III)-catalyzed redox-neutral C7-selective C-H functionalization of indolines with arylalkynes is described to directly access 7-membered 1,7-fused indolines. Moreover, an unprecedented intramolecular addition of an alkenyl-Cp*Rh(III) species to a carbamoyl moiety occurred to give 1H-pyrroloquinolinones when employing alkyl alkynes. Additionally, an efficient Rh(III)-catalyzed redox-neutral C7-selective C-H activation/alkenylation/aza-Michael addition of indolines is also developed to give 6-membered 1,7-fused indolines. The advantages of these processes are as follows: (1) mild and simple reaction conditions; (2) no need for an external oxidant; (3) broad scope of substrates; and (4) valuable six- or seven-membered 1,7-fused indolines as products.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkenes / chemistry
  • Alkynes / chemistry
  • Catalysis
  • Cyclization
  • Hydrogen Bonding
  • Indoles / chemical synthesis*
  • Indoles / chemistry
  • Molecular Structure
  • Oxidants / chemistry*
  • Oxidation-Reduction
  • Rhodium / chemistry*

Substances

  • Alkenes
  • Alkynes
  • Indoles
  • Oxidants
  • indoline
  • Rhodium