Transformation of 3-(Furan-2-yl)-1,3-di(het)arylpropan-1-ones to Prop-2-en-1-ones via Oxidative Furan Dearomatization/2-Ene-1,4,7-triones Cyclization

Abstract

The approach to 3-(furan-2-yl)-1,3-di(het)arylprop-2-en-1-ones based on the oxidative dearomatization of 3-(furan-2-yl)-1,3-di(het)arylpropan-1-ones followed by an unusual cyclization of the formed di(het)aryl-substituted 2-ene-1,4,7-triones has been developed. The cyclization step is related to the Paal–Knorr synthesis, but the furan ring formation is accompanied in this case by a formal shift of the double bond through the formation of a fully conjugated 4,7-hydroxy-2,4,6-trien-1-one system or its surrogate.

Oxidative Transformation of 2-Furylanilines into Indolin-3-ones

“…After some experimentation, we detected that treating compound 1a with m -CPBA in DCM led to a full conversion within 3 h providing unsaturated diketone 2a in almost quantitative yield as a mixture of Z- and E- isomers (Scheme ). It was noted that diketone 2a was further slowly transforming into indolin-3-one 3a upon standing, so we screened the conditions for selective follow-up cyclization. Triethylamine was found to effectively facilitate the cyclization process, and the target indolin-2-one 3a was obtained with 89% yield.…”

Oxidative Spirocyclization of β-Furyl Amides for the Assembly of Spiro-γ-butenolide-γ-butyrolactones

“…Having established the efficacy of the one-pot synthesis of γ-spirobutenolides, we were interested in probing the reaction mechanism. Several examples of β-furyl carbonyl oxidations have been previously reported, − some of which propose spirocyclic intermediates . To observe reaction intermediates, a solution of β-furyl amide 1d and the phenanthrene internal standard was prepared in CDCl 3 (Figure a, t = 0 min).…”