Blue LED photolytic method for the synthesis of 1,4-dihydropyridine derivatives from benzo [b]thiophene-2-carbaldehyde

Abstract

This study presents a highly efficient and operationally simple protocol for synthesizing 1,4-dihydropyridine derivatives. The protocol uses an inexpensive and readily available photocatalyst Mn₂(CO)₁₀, which plays a crucial role in the single-pot, four-component reaction involving benzo [b]thiophene-2-carbaldehyde, malononitrile, dialkyl acetylene dicarboxylate, and anilines in a blue LED (400–500 nm) photocatalytic technique. The reaction conditions include the use of blue LEDs, a lower catalyst load, and green solvents like dimethyl sulfoxide (DMSO) and water in a 1:1 ratio. The multicomponent photocatalytic approach negates the use of expensive catalysts and the necessity of multi-step routes, in addition to providing better atom economy and an easy work-up process, and it is environmentally benign. The derivatives were effectively synthesized in higher yields and characterized using ¹H NMR, ¹³C NMR, and ESI-MS. The obtained 1,4 dihydropyridines also have tremendous capability for biological and pharmacological activities, opening exciting possibilities for future research and applications.