Visible Light Mediated, Catalyst Free, One-Pot Convenient Synthesis of Dihydropyridines

Abstract

: A simple, efficient and green protocol has been developed for the synthesis of polysubstituted dihydropyridines via one-pot, four-component reaction of aldehydes, arylamines, dialkyl acetylenedicarboxylate, and malononitrile. The reaction was proceeded at room temperature in the absence of catalyst in aqueous ethyl lactate under visible light irradiation. The main advantages of the present approach are mild reaction condition, high yield, no column chromatography, clean reaction profile, environmentally friendly and sustainable from the economic point of view

Visible-light-induced organophotocatalytic and singlet oxygen-initiated domino construction of 1,4-dihydropyridines, C-3 functionalized spiro[indoline-3,4′-pyridines] and C-11 functionalized spiro[indeno-[1,2-b]quinoxaline-11,4′-pyridines]

“…Consequently, several synthetic approaches, from the traditional Hantzsch 31 reaction to many more, have been devised to assemble 1,4-dihydropyridines (Scheme 1a). Alternatively, there are limited reports on the synthesis of 1,4-DHPs based on a four-component reaction of aldehydes, active methylene compounds, dialkyl acetylene dicarboxylates, and amines using various catalytic systems including piperidine, 32 Fe 3 O 4 @SiO 2 –NH 2 , 33 Y 2 O 3 /ZrO 2 , 34 [3,6-DOMDA]OTf, 35 KF/Al 2 O 3 , 36 CuI, 37 and Sm 2 O 3 /ZrO 2 , 38 and under catalyst-free conditions 39–42 (Scheme 1b & c 43,44 ). In spite of the tremendous features offered by the developed strategies, the requirements of transition metal catalysts, volatile organic solvents, lengthy and laborious work-up procedures, high energy input, harsh reaction conditions, limited functional group tolerance, and relatively low yields of products mark the shortcomings of the processes.…”