A ring expansion-annulation strategy for the synthesis of substituted azulenes. Preparation and Suzuki coupling reactions of 1-azulenyl triflates

Org Lett. 2001 Apr 5;3(7):1081-4. doi: 10.1021/ol0156897.

Abstract

[structure: see text]. A new strategy for the synthesis of substituted azulenes is reported, based on the reaction of beta'-bromo-alpha-diazo ketones with rhodium carboxylates. The key transformation involves intramolecular addition of a rhodium carbenoid to an arene pi-bond, electrocyclic ring opening, beta-elimination, tautomerization, and trapping to produce 1-hydroxyazulene derivatives. The synthetic utility of the method is enhanced by the ability of the triflate derivatives to participate in Suzuki coupling reactions, as illustrated in a synthesis of the antiulcer drug egualen sodium (KT1-32).

Publication types

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

MeSH terms

  • Anti-Inflammatory Agents, Non-Steroidal / chemical synthesis*
  • Anti-Ulcer Agents / chemical synthesis*
  • Azulenes
  • Benzene / chemistry
  • Cycloheptanes / chemical synthesis*
  • Humans
  • Ketones / chemistry
  • Molecular Structure
  • Rhodium / chemistry*
  • Sesquiterpenes / chemical synthesis*

Substances

  • Anti-Inflammatory Agents, Non-Steroidal
  • Anti-Ulcer Agents
  • Azulenes
  • Cycloheptanes
  • Ketones
  • Sesquiterpenes
  • sodium 3-ethyl-7-isopropyl-1-azulenesulfonate
  • azulene
  • Rhodium
  • Benzene