Lanthanum(III)-Catalyzed Three-Component Reaction of Coumarin-3-carboxylates for the Synthesis of Indolylmalonamides and Analysis of Their Photophysical Properties

Abstract

New methodology has been developed for the Lewis acid catalyzed synthesis of malonamides. First, the scandium(III)-catalyzed addition of diverse nucleophiles (e.g., indoles, N,N-dimethyl-m-anisidine, 2-ethylpyrrole, and 2-methylallylsilane) to coumarin-3-carboxylates has been developed to afford chromanone-3-carboxylates in high yields as a single diastereomer. Upon investigating a subsequent lanthanum(III)-catalyzed amidation reaction, a new multicomponent reaction was designed by bringing together coumarin-3-carboxylates with indoles and amines to afford indolylmalonamides, which were identified to exhibit fluorescent properties. The photophysical properties for selected compounds have been analyzed, including quantum yield, molar absorptivity, and Stokes shift. Synthetic studies of several reaction byproducts involved in the network of reaction equilibria for the three-component reaction provide mechanistic insight for the development of this methodology.

Synthesis, characterizations and photo-physical properties of novel lanthanum(III) complexes

“…One of the early lanthanide elements, lanthanum, is itself used in the field of ceramics, thermal stability, solar energy, catalysis, photostrictor, dye sensitizers, scintillators, optoelectronic and photonic studies [3][4][5][6][7][8][9][10][11][12]. Due to wide applications in the field of luminescence [13][14][15], lanthanum is attracting the attention in the photo-physical research area. The term photophysical is mainly concerned with the absorption, excitation and emission processes [16,17], which leads to the luminescence characteristics.…”

Recent advances in the application of indoles in multicomponent reactions

“…45 Indolylmalonamide products 33 showed notable uorescence activities when they are exposed to long wave UV light (366 nm).…”

Highly efficient catalyst-free domino conjugate addition, decarboxylation and esterification/amidation of coumarin carboxylic acid/esters with pyrazolones: a green chemistry approach

“…Recently, Xiao et al 27 reported the synthesis of 3,4-dihydrocoumarines via the addition/decarboxylation of coumarin/ thiocoumarin carboxylic acids with indole (Scheme 1). Franz et al 28 disclosed the La(OTf) 3 -catalysed three-component reaction of coumarin 3 carboxylates for the synthesis of indolylmalonamides. Lin et al 29 reported the a-addition of gbutyrolactums to coumarin derivatives, and Han et al 30 reported the Rh-catalysed C sp 2 -H arylation of coumarins for the synthesis of 3,4-dihydro coumarins.…”