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Divergent Conversion of 4‑Naphthoquinone-substituted 4H‑Isoxazolones to Different Benzo-fused Indole Derivatives
journal contribution
posted on 2020-03-17, 19:44 authored by Michael
S. Christodoulou, Sabrina Giofrè, Egle M. Beccalli, Francesca Foschi, Gianluigi Broggini4,4-Disubstituted
4H-isoxazol-5-ones bearing a
1,4-naphthoquinone moiety undergo transformation into different types
of benzoindolyl products depending on the different reaction conditions.
A decarboxylative ring opening/ring closure promoted by catalytic
[Ru(p-cymene)2Cl2]2 yields benzo[f]indole-4,9-diones. Alternatively,
hydrogenation reactions provide the conversion of 4-(1,4-naphthoquinone)-substituted
isoxazol-5-ones to benzo[g]indole compounds, with
the level of reduction depending on the substituents present on the
ring. Starting materials have been easily prepared by the functionalization
of isoxazolinones with naphthoquinone under mild conditions.