Metathesis reactions for the synthesis of ring-fused carbazoles.
[reactions: see text] The metathesis reaction is used as a key step for the synthesis of the indolo[2,3-a]carbazole core of rebeccamycin 13 and the sulfur analog of furostifoline 21. Using the same methodology for the attempted synthesis of furostifoline, we unexpectedly formed tert-butyl-2a-methyl-1,2,2a,10c-tetrahydro-6H-cyclobuta[c]furo[3,2-a]carbazole-6-carboxylate 26 from the unstable diene, tert-butyl 2-(2-isopropenyl-3-furyl)-3-vinyl-1H-indole-1-carboxylate 25, presumably via a spontaneous pi8 electrocyclization reaction.
Pelly
Stephen C
SC
Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, P.O. Wits, 2050 South Africa.
Parkinson
Christopher J
CJ
van Otterlo
Willem A L
WA
de Koning
Charles B
CB
D002227:Carbazoles / Q000138:chemical synthesis*; D003500:Cyclization; D007211:Indoles / Q000138:chemical synthesis; D009682:Magnetic Resonance Spectroscopy
D002227:Carbazoles; D007211:Indoles; C053339:rebeccamycin