Diels–Alder reactivity of pyrano[4,3-b]indol-3-ones, indole 2,3-quinodimethane analogues
1990; Issue: 3 Linguagem: Inglês
10.1039/p19900000673
ISSN2050-8255
AutoresChristopher J. Moody, Kulsum F. Rahimtoola,
Tópico(s)Synthesis of Organic Compounds
ResumoThe pyrano[4,3-b]indol-3-ones (7) are stable indole-2,3-quinodimethane type dienes, which undergo Diels–Alder reaction with alkynes to give, after loss of carbon dioxide, carbazoles. The reactivity of the diene is increased by the presence of the electron-withdrawing t-butoxycarbonyl group on the indole nitrogen. The pyranoindolones (7) are less reactive, and exhibit the opposite regiochemistry in their Diels–Alder reactions than the isomeric pyrano[3,4-b]indol-3-ones (1). Factors which affect the regiochemistry of the Diels–Alder reaction are discussed.
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