A ring expansion-annulation strategy for the synthesis of substituted azulenes. Preparation and Suzuki coupling reactions of 1-azulenyl triflates.
[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).
Department of Chemistry, Massachusetts Institute of Technology Cambridge, Massachusetts 02139, USA.
J L
JL
Kane
K M
KM
Shea
A L
AL
Crombie
R L
RL
Danheiser
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000138:chemical synthesis*; D000897:Anti-Ulcer Agents / Q000138:chemical synthesis*; D052176:Azulenes; D001554:Benzene / Q000737:chemistry; D003508:Cycloheptanes / Q000138:chemical synthesis*; D006801:Humans; D007659:Ketones / Q000737:chemistry; D015394:Molecular Structure; D012238:Rhodium / Q000737:chemistry*; D012717:Sesquiterpenes / Q000138:chemical synthesis*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D000897:Anti-Ulcer Agents; D052176:Azulenes; D003508:Cycloheptanes; D007659:Ketones; D012717:Sesquiterpenes; C403723:sodium 3-ethyl-7-isopropyl-1-azulenesulfonate; C005525:azulene; D012238:Rhodium; D001554:Benzene