Sequential Diels-Alder reaction of in situ generated 2,3-dimethylenepyrrole and carbodienophiles: rapid synthesis of 2,3,6,7-tetrasubstituted carbazoles
[reaction: see text] 2,3,6,7-Tetrasubstituted-1,2,3,4,5,6,7,8-octahydrocarbazoles 2 were synthesized in 46-90% yields by sequential Diels-Alder reactions from N-benzyl-2,5-dimethyl-3,4-bisacetoxymethylpyrrole (1) and dienophiles such as maleic anhydride, maleimides, ethyl maleate, fumaronitrile, and ethyl acrylate. The 2,3,6,7-tetrasubstituted carbazoles 3 were then synthesized in 32-87% yields from 2 by oxidation with DDQ.
Vessels
JT
Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana 61801, USA.
Janicki
SZ
Petillo
PA