A new multicomponent approach to the synthesis of substituted furan-2(5H)-ones containing 4H-chromen-4-one fragment

Aryl glyoxal: a prime synthetic equivalent for multicomponent reactions in the designing of oxygen heterocycles

The category of bifunctional building blocks overrides many others because of their fascinating wide applicability in synthetic chemistry. Aryl glyoxal is one of the key molecules that has been extensively used in heterocyclic chemistry to afford nearly all types of five- and six-membered heterocycles, which are the structural constituents of many natural products. The multicomponent reaction is a practical strategy to utilize this wonderful moiety with different types of starting materials to obtain numerous diverse oxygen heterocycles. This review covers the advancement of aryl glyoxal as a prime synthetic equivalent in recent years for the synthesis of oxygen heterocycles.

Metal-free synthesis of dihydrofuran derivatives as anti-vicinal amino alcohol isosteres

Dihydrofuran cores are commonly incorporated into synthetically and pharmacologically significant scaffolds in natural product and drug discovery chemistry. Herein, we report a concise and practical strategy to construct spiro-dihydrofuran and amino dihydrofuran scaffolds as anti-vicinal amino alcohol isosteres. Hypervalent iodine (PhI(OAc)(NTs₂))-mediated C-H activation of alkynes resulted in two-bond formations with one pi bond cleavage: (i) C(sp²)-N(sp³) and O(sp³)-C(sp²); (ii) C(sp²)-N(sp³) and C(sp³)-C(sp²). The metal-free 5-endo-dig oxidative cyclization provided versatile amino 2,3- and 2,5-dihydrofurans bearing the C₅ quaternary carbon. The non-toxicity of all synthesised dihydrofurans was verified via in vitro cell viability assay.

2-(5-Acetyl-7-methoxy-2-(4-methoxyphenyl)benzofuran-3-yl)acetic Acid

We elaborated a convenient one-step approach for the synthesis of previously unknown 2-(5-acetyl-7-methoxy-2-(4-methoxyphenyl)benzofuran-3-yl)acetic acid. The suggested protocol includes the multicomponent reaction of acetovanillone, 4-methoxyphenylglyoxal and Meldrum’s acid. We have demonstrated that the considered reaction is a one-pot telescoped process including the preliminary condensation of the components in MeCN followed by acid-catalyzed cyclization. The structure of the synthesized product was confirmed by 1H, 13C-NMR spectroscopy and high-resolution mass-spectrometry.

2-(2-(4-Methoxyphenyl)furo[3,2-h]quinolin-3-yl)acetic Acid

A simple and efficient protocol for the synthesis of the previously unknown 2-(2-(4-methoxyphenyl)furo[3,2-h]quinolin-3-yl)acetic acid was elaborated. The suggested method is based on the telescoped multicomponent reaction of 8-hydroxyquinoline, 4-methylglyoxal, and Meldrum’s acid. The studied process includes the initial interaction of the starting compounds in MeCN followed by intramolecular cyclization to the target product in refluxing acetic acid. The advantage of this approach is the application of readily available starting materials, atom economy, and a simple work-up procedure. The structure of the synthesized furylacetic acid derivative was proven by 1H, 13C, 2D-NMR, IR spectroscopy, and high-resolution mass spectrometry.

2-(2-(4-Methoxyphenyl)-4,9-dimethyl-7-oxo-7H-furo[2,3-f]chromen-3-yl)acetic Acid

For the first time, we describe a new approach towards the synthesis of previously unknown 2-(2-(4-methoxyphenyl)-4,9-dimethyl-7-oxo-7H-furo[2,3-f]chromen-3-yl)acetic acid. The presented method is based on the multicomponent condensation of 5-hydroxy-4,7-dimethyl-2H-chromen-2-one, 4-methoxyphenylglyoxal and Meldrum’s acid. It was shown that the studied reaction proceeds in two steps including the initial interaction of starting materials in MeCN and the final formation of furylacetic acid moiety in acidic media. The structures of the obtained compound were established by 1H, 13C-NMR spectroscopy and high-resolution mass spectrometry.

Multicomponent Approach to the Synthesis of 4-(1H-indol-3-yl)-5-(4-methoxyphenyl)furan-2(5H)-one

A simple one-pot approach was developed for the synthesis of furan-2(5H)-one derivative containing indole fragments. This method includes the telescoped multicomponent reaction of indole, 4-methoxyphenylglyoxal, and Meldrum’s acid. The synthetic utility of the prepared furan-2(5H)-one was demonstrated by condensation with 4-methoxybenzaldehyde. The advantages of this method include the employment of readily accessible starting materials, atom economy, process simplicity, and the easy isolation of the target products. The structure of the synthesized furanones was confirmed by 1H and 13C-NMR spectroscopy and high-resolution mass spectrometry with electrospray ionization (ESI-HRMS).