Allenyl azide cycloaddition chemistry. 2,3-cyclopentennelated indole synthesis through indolidene intermediates

J Org Chem. 2009 Jul 17;74(14):4958-74. doi: 10.1021/jo900659w.

Abstract

The thermal, photochemical, and photochemical/CuI-mediated cascade cyclizations of a range of substituted 1-(2-azidophenyl)-3-alkenylallenes are described. These reactions provide both 1,2- and 2,3-cyclopentennelated indole products in varying ratios. In most cases, high regioselectivity for the 2,3-annelated isomer can be achieved under the hnu/CuI conditions. Computational studies of this multistep reaction support the intermediacy of indolidene intermediates whose electrocyclizations (with or without copper present) define the regioselectivity branch point in the sequence.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Azides / chemistry*
  • Computer Simulation
  • Copper / chemistry
  • Cyclization
  • Indoles / chemical synthesis*
  • Indoles / chemistry
  • Light
  • Molecular Structure
  • Stereoisomerism
  • Thermodynamics

Substances

  • Azides
  • Indoles
  • Copper