Synthesis of Chromeno[4,3‐b]pyrrol‐4(1H)‐ones, from β‐Nitroalkenes and 4‐Phenylaminocoumarins, under Solvent–free Conditions

Abstract

A new approach toward chromeno[4,3‐b]pyrrol‐4(1H)‐ones, by annulation of 4‐phenylaminocoumarins with β‐nitroalkenes, is reported and its conditions were optimized. The transformations under the fine‐tuned conditions took place under promotion by TsOH.H2O, in the absence of solvent. The scope and limitations of the process were explored, by systematic modification of two diversification points. A reaction mechanism, triggered by a Michael addition of the nitrogen moiety of the 4‐phenylaminocoumarins to the β‐nitroalkene, was also proposed. Further functionalization of a selected tricycle was performed; the photophysical (UV and fluorescence spectra; 1O2 generation) and electrochemical (cyclic voltammetry) properties of some heterocycles were studied.

Facile and Green One‐Pot Synthesis of Fluorophore Chromeno[4,3‐b]quinolin‐6‐one Derivatives Catalyzed by Halloysite Nanoclay under Solvent‐free Conditions

“…Coumarin derivatives display interesting fluorescence properties which are known to absorb in the UV‐vis region and show fluorescence –. In this respect, we observed some prepared chromeno[4,3‐ b ]quinolin‐6‐ones displayed as motivating fluorophore compounds during our work.…”

Synthetic Routes to Coumarin(Benzopyrone)-Fused Five-Membered Aromatic Heterocycles Built on the α-Pyrone Moiety. Part 1: Five-Membered Aromatic Rings with One Heteroatom

“…Many synthetic protocols have been reported for the synthesis of [l]benzopyrano [4,3- b ]pyrrole-4(1 H )-ones, including the reaction of β-nitroalkenes 67 and 4-phenylamino coumarins 66 under solvent-free conditions to afford 68 ( Scheme 20 ) [ 69 ]. Moreover, the reaction of the 4-aminocoumarin ( 69 ), amines 70 , and glyoxal monohydrates 71 in the presence of nanocrystalline CuFe 2 O 4 [ 70 ], or KHSO 4 , led to the formation of [l]benzopyrano [4,3- b ]pyrrole-4(1 H )-ones 72 ( Scheme 21 ) [ 71 ].…”

Application of β‐Nitrostyrene in Multicomponent Reactions for the Synthesis of Pyrrole Derivatives

“…Other catalysts such as CSA ⋅ H 2 O, Amberlyst‐15, FeCl 3 ⋅ 6H 2 O, Ce(OTf) 3 was tested in CH 3 NO 2 , toluene and under solvent‐free conditions that the best result was obtained using TsOH (20 mol %) in solvent‐free conditions at 120 °C (Scheme ). The plausible mechanism for the synthesis of Chromeno[4,3‐b]pyrrol‐4(1 H )‐ones is illustrated in (Scheme ) …”