Microwave-Assisted Fluorous Multicomponent Reactions – A Combinatorial Chemistry Approach for Green Organic Synthesis

Multicomponent reactions in unconventional solvents: state of the art

“…Fluorous separation technology has also been examined in some multicomponent reactions, which improve the MCRs in terms of energy efficiency, atom economy, easy purification, and reduced amount of waste solvents. 314 However, in these cases, fluorous substances mainly play the role of liquid supports but not solvents. Therefore our review will not discuss these examples in detail.…”

TiCl4-promoted condensation of methyl acetoacetate, isobutyraldehyde, and indole: a theoretical and experimental study

“…The study revealed that titanium plays a key role in the reaction: (1) it increases the acidity of the active methylene compound, allowing the easy generation of the active species (enolate); (2) it coordinates both enolate and aldehyde, promoting the aldol condensation; (3) it favors the intramolecular elimination of the titanyl group with generation of the Knoevenagel adduct; (4) it increases the electrophilicity of the Knoevenagel adduct by complexation; (5) it orientates the attack of indole at C b of the Knoevenagel adduct by favoring the formation of hydrogen bonds between the indole N-H group and the titanium ligands; and (6) it stabilizes the anionic intermediate 8 by electronic delocalization towards metal ligands. In terms of electronic structure, the promoting effect of Ti(IV) can be ascribed to its electron-poor nature.…”

“…They are widely used in combinatorial chemistry to synthesize libraries of compounds having a common scaffold. 4,5 They are also increasingly used in diversityoriented synthesis to generate compounds with high structural diversity. [6][7][8] In this context, we have previously reported a TiCl 4 -promoted trimolecular condensation of aromatic heterocycles, aldehydes, and carbonyl derivatives to afford polyfunctionalized heterocycles (Scheme 1).…”

Diversity Oriented Syntheses of Conventional Heterocycles by Smart Multi Component Reactions (MCRs) of the Last Decade

“…Here the reactants have been highly non-polar. Reviews on the usage of MW in syntheses of heterocycles by MCRs are given [ 118 , 119 , 120 , 121 ]. An alternative energy source for reaction activation, even without solvents, is IR [ 122 ].…”