Synthesis of 4-aminoguaiazulene and its δ-lactam derivatives
摘要:
A method for nitrogen insertion into guaiazulene hydrocarbons is developed. A one-pot reaction of 7-isopropyl-1-methylazulene-4-carboxylic acid, diphenylphosphoryl azide, and an alcohol (MeOH, BuOH or BnOH) affords the corresponding carbamates. Deprotection of benzyl (7-isopropyl-1-methylazulen-4-yl)carbamate under basic conditions gave 4-aminoguaiazulene, which undergoes ring annulation reactions with 1,2-dicarbonyl reagents to yield tricyclic delta-lactams. (C) 2011 Elsevier Ltd. All rights reserved.
4,4′-Biazulene has been synthesized by the combination of decarbonylative borylation, iodination and Suzuki-Miyaura cross-coupling and characterized by spectroscopic and crystallographic methods. The racemization energy barrier of 4,4′-biazulene is comparable to that of isomeric 1,1′-binaphthyl.