Regiodivergent condensation of 5-alkoxycarbonyl-1H-pyrrol-2,3-diones with cyclic ketazinones en route to spirocyclic scaffolds

• Alexey Yu. Dubovtsev,
• Maksim V. Dmitriev,
• Аndrey N. Maslivets and
• Michael Rubin

Beilstein J. Org. Chem. 2017, 13, 2179–2185, doi:10.3762/bjoc.13.218

• Chemistry, University of Kansas, 1251 Wescoe Hall Dr., Lawrence, KS 66045-7582, USA 10.3762/bjoc.13.218 Abstract The condensation of 5-alkoxycarbonyl-1H-pyrrolediones with cyclic ketazinones was systematically investigated. It was discovered that the regioselectivity of this reaction can be easily swapped

• between two alternative directions affording derivatives of partially hydrogenated indole or benzofurane. The control of this regioselectivity is efficiently governed by steric effects at the hydrazone moiety of the ketazinone reagent. Keywords: nitrogen heterocycles; oxygen heterocycles; pyrrolediones

• cyclocondensation of six-membered cyclic enamines 1 (vinylogous secondary amides) with 5-methoxycarbonyl-1H-pyrrolediones 2 [39][40][41]. This transformation involved the Michael addition of an enamine to the α,β-unsaturated carbonyl fragment of a pyrroledione and subsequent 5-exo-trig intramolecular nucleophilic