Intramolecular Nicholas Reactions in the Synthesis of Dibenzocycloheptanes. Synthesis of Allocolchicine NSC 51046 and Analogues and the Formal Synthesis of (−)-Allocolchicine
作者:Sinisa Djurdjevic、Fei Yang、James R. Green
DOI:10.1021/jo101953n
日期:2010.12.3
The preparation of dibenzocycloheptyne-Co2(CO)6 complexes by intramolecular Nicholas reactions of biaryl-2-propargyl alcohol-Co2(CO)6 derivatives is described. Reductive decomplexation of the dibenzocycloheptyne-Co2(CO)6 complexes affords the corresponding dibenzocycloheptenes, individual members of which have been employed in a formal total synthesis of (−)-allocolchicine, the preparation of 6,7-dihydro-3
Allocolchicines via Intramolecular Nicholas Reactions: The Synthesis of NSC 51046
作者:Sinisa Djurdjevic、James R. Green
DOI:10.1021/ol7024422
日期:2007.12.1
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).