Intramolecular Nicholas reactions in the synthesis of dibenzocycloheptanes. Synthesis of allocolchicine NSC 51046 and analogues and the formal synthesis of (-)-allocolchicine.
The preparation of dibenzocycloheptyne-Co(2)(CO)(6) complexes by intramolecular Nicholas reactions of biaryl-2-propargyl alcohol-Co(2)(CO)(6) derivatives is described. Reductive decomplexation of the dibenzocycloheptyne-Co(2)(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-3,4,9,10,11-pentamethoxy-5H-dibenzo[a,c]cyclohepten-5-one, and the enantioselective total syntheses of NSC 51046 and its 3,8,9,10-tetramethoxy regioisomer.
Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4, Canada.
Sinisa
S
Djurdjevic
Fei
F
Yang
James R
JR
Green
D000480:Alkynes / Q000737:chemistry*; D003078:Colchicine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D003986:Dibenzocycloheptenes / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D020005:Propanols / Q000737:chemistry*; D013237:Stereoisomerism
D000480:Alkynes; D003986:Dibenzocycloheptenes; C555845:NSC 51046; D020005:Propanols; C032782:allocolchicine; C028255:propargyl alcohol; D003078:Colchicine