Allocolchicines via intramolecular Nicholas reactions: the synthesis of NSC 51046.
Biaryl propargyl acetate hexacarbonyldicobalt complexes (4) undergo Lewis acid mediated Nicholas reactions with a remote arene function to afford dibenzocycloheptyne complexes (9). Reductive decomplexation based on a hydrosilylation-protodesilylation protocol is facile, and the 1,2,3,9-tetramethoxy case can be converted to NSC 51046 ((S)-N-acetylcolchicinol methyl ether, 3).
Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada N9B 3P4.
Sinisa
S
Djurdjevic
James R
JR
Green
D003078:Colchicine / Q000737:chemistry*; D003500:Cyclization
D003078:Colchicine