Facile and Chemically Sustainable Catalyst‐Free Synthesis of Diverse 2‐Aryl‐4‐Alkyl/Aryl‐Pyrano[3,2‐c]chromen‐5(4H)‐Ones by One‐Pot Multicomponent Reactions at Room Temperature

Abstract

A simple, catalyst‐free, straightforward and highly efficient one‐pot synthesis of pharmaceutically‐interesting diverse kind of functionalized 2‐aryl‐4‐alkyl/aryl‐pyrano[3,2‐c]chromen‐5(4H)‐ones (4 a‐4 z′′) and 3‐/4‐(5‐oxo‐2‐aryl‐4,5‐dihydropyrano[3,2‐c]chromen‐4‐yl)benzaldehydes (4′a‐4′j) has been developed based on a multicomponent reaction between alkyl/aryl aldehydes (1/1′), acetophenones (2) and 4‐hydroxycoumarin (3) in aqueous ethanol at room temperature (25‐30 °C). The salient features of this protocol are mild reaction conditions, use of no catalyst, good to excellent yields, high atom‐economy, eco‐friendliness, easy isolation of products, and reusability of reaction media.

Catalyst-Free One-Pot Three-Component Synthesis of Diversely Substituted 5-Aryl-2-oxo-/thioxo-2,3-dihydro-1H-benzo[6,7]chromeno[2,3-d]pyrimidine-4,6,11(5H)-triones Under Ambient Conditions

“…On the basis of the critical survey of the literature on catalystfree organic transformations coupled with our own experience in performing this kind of organic synthesis, 69 we envisioned that such a 1H-benzo [6,7]chromeno [2,3-d]pyrimidine scaffold might be constructed out of a one-pot MCR of its starting constituents such as barbituric acid, aldehyde, and 2-hydroxy-1,4-naphthoquinone without the aid of any catalyst in the presence of a suitable solvent. First, we checked our model reaction between barbituric acid (1-1; 1 equiv), benzaldehyde (2-1; 1 equiv), and 2-hydroxy-1,4-naphthoquinone (3; 1 equiv) in the absence of any catalyst in aqueous medium under ambient conditions, thereby isolating the desired compound, 5phenyl-1H-benzo [6,7] characterized by its analytical and spectral properties.…”

Development of a Water-Mediated and Catalyst-Free Green Protocol for Easy Access to a Huge Array of Diverse and Densely Functionalized Pyrido[2,3-d:6,5-d′]dipyrimidines via One-Pot Multicomponent Reaction under Ambient Conditions

“…Based on critical survey of the literature on catalyst-free organic transformations coupled with our own experiences in performing this kind of organic syntheses, , we envisioned that such a 9,10-dihydropyrido­[2,3- d :6,5- d ′]­dipyrimidine-2,4,6,8­(1 H ,3 H ,5 H ,7 H )-tetraone scaffold might be constructed out of a one-pot multicomponent reaction of its starting constituents such as barbituric acid, amine, and aldehyde without the aid of any catalyst in the presence of a suitable solvent. First we checked our model reaction with a mixture of barbituric acid ( 1 - 1 ; 2.0 equiv), aniline ( 2 - 1 ; 1.0 equiv), and 4-nitrobenzaldehyde ( 3 - 1 ; 1.0 equiv) in the absence of any catalyst in aqueous medium (4 mL) under ambient conditions.…”

Revisiting Biginelli-like reactions: solvent effects, mechanisms, biological applications and correction of several literature reports

“…12 Catalyst-free versions, conducted in alternative green solvents, follow the same trend, where Scheme 2 Examples of Biginelli-like multicomponent transformations: (I) 1,4-dihydropyrimidine (DHP) synthesis, [78][79][80][81] (II) 2-amino-3-cyano-4Hpyrans (ACP) derivatives, 82,83 (III) 3,4-dihydro-2H-chromeno [4,3-d]pyrimidine-2,5(1H)-dione or thione (CPD) derivatives, 82,[84][85][86][87][88][89][90][91][92][93][94][95][96][97][98][99][100][101][102] and (IV) pyrano[3,2c]chromen-5(4H)-ones (PCC) compounds. [103][104][105][106] Fig. 1 Melting points descriptions for the claimed structure of CPD-01.…”