129720-06-5Relevant academic research and scientific papers
Efforts directed toward the synthesis of colchicine: Application of palladium-catalyzed siloxane cross-coupling methodology
Seganish, W. Michael,Handy, Christopher J.,DeShong, Philip
, p. 8948 - 8955 (2007/10/03)
Colchicine is an important and synthetically challenging natural product. The key synthetic step in this approach to the synthesis of colchicine involved a palladium-catalyzed cross-coupling reaction between 5-bromotropolone (4) and an aryl siloxane to form the aryl-tropolone bond. The coupling of a variety of highly functionalized aryl siloxane derivatives was investigated and optimized coupling conditions were developed. It was discovered that a palladium catalyst with a high degree of phosphine ligand coordination (5 equiv of phosphine/mol Pd) was necessary to efficiently couple aryl siloxanes with 5-bromotropolone (4). In addition, the coupling approach has provided a direct comparison between siloxane and boronic acid coupling technologies that demonstrated that aryl siloxanes and boronic acids produce similar yields of highly functionalized biaryl products.
The Palladium-Mediated Cross Coupling of Bromotropolones with Organostannanes or Arylboronic Acids: Applications to the Synthesis of Natural Products and Natural Product Analogues
Banwell, Martin G.,Cameron, Jennifer M.,Collis, Maree P.,Crisp, Geoffrey T.,Gable, Robert W.,'et al.
, p. 705 - 728 (2007/10/02)
The bromotropolones (4), (5) and (10) undergo palladium-mediated cross coupling with a wide range of organostannanes to produce alkenyl-, alkyl- and aryl-substituted tropolones.The methodology has been applied to the synthesis of the monoterpenes β-dolabrin (11), β-thujaplicin (12), 4-isopropyl-7-methoxytropolone (13) and β-thujaplicinol (14).Cross coupling of bromotropolones (4), (5) and (10) with various aryltrimethylstannanes or arylboronic acids has permitted the preparation of the bicyclic colchicine analogues (30)-(43) which have been tested for tubulin-binding activity.The X-ray crystal structure of the most active of these systems, compound (38), is reported.
