Ordered short channel mesoporous silica modified with 1,3,5-triazine–piperazine as a versatile recyclable basic catalyst for cross-aldol, Knoevenagel and conjugate addition reactions with isatins

Abstract

ARTICLE This journal isAbstract: A triazine-piperazine immobilized on ordered short channel mesoporous silica was synthesized, characterized and used as heterogeneous base catalyst in the synthesis of indole skeletal structure from isatin derivatives under ambient reaction condition in good to excellent isolated yields. The catalyst showed no loss in its efficacy over 10 recycle experiments.

Spiro[4H‐2,3‐dihydropyran‐3,3′‐oxindoles] derived from 1,2,3,4‐tetrahydroquinoline

“…Exactly comparable structures have been obtained from the reactions of isatin itself and benzene‐ring‐substituted isatins . We believe that the sequence (Scheme shows malononitrile and cyclohexane‐1,3‐dione) commences with a Knoevenagel condensation between the reactive isatin 3‐ketone, and the active methylene of the malononitrile, as shown, giving 7 (condensation with the 1,3‐diketone might also be the initiating step – both condensations are known ). Following the condensation, 1,3‐diketone enolate Michael‐type addition to the conjugated system (or malonate anion addition if the first step was condensation with the diketone) generates a second carbon–carbon bond in structure 8 from whence via deprotonation and cyclization involving enolate oxygen addition to one of the nitriles (arrows on 8 ) leads to the final product 4 .…”

A novel three-position molecular switch based on the transformations of a cyano-substituted pyrrol-2-one derivative

“…Looking for options for the synthesis of the desired OTCP, it was found that a common method for the preparation of various 3-ylidenemalononitrile derivatives of pyrrol-2-one is the reaction of pyrrole-2,3-diones with malononitrile. [22][23][24] However, such an approach was never used to create any OTCP derivatives. In this regard, at the initial stage, the synthesis of pyrrole-2,3-dione 2 bearing a cyano group in the fourth position, which was necessary for the further creation of the BDTC fragment, was carried out.…”

Highly dispersible bis-imidazolium/WO42− modified magnetic nanoparticles: a heterogeneous phase transfer catalyst for green and selective oxidations

“…This reaction was conducted at a low temperature to avoid further substitutions. [48][49][50][51][52][53][54] The next step was the replacement of two other chlorides with N-methylimidazole to produce an ionic liquid (IL) ligand with chlorides as counter ions (MNP@IL/Cl). 48,49 The final step was the exchange of the chloride ions with tungstate to create the final catalyst (MNP@IL/W).…”