Leucine: green and efficient catalyst for the synthesis of 4H-chromenes

Abstract

Leucine, a naturally occurring α-amino acid, has been found as an effective catalyst to effect the one-pot three-component condensation reaction between aromatic aldehydes, malononitrile and 5,5-dimethyl-1,3-cyclohexanedione (dimedone). Various 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile derivatives are conveniently prepared by these reactions in excellent yields. High yields, short reaction times, simple work-up, use of green and naturally occurring catalyst and solvent are the main merits of the present protocol.

N‐(3‐silyl propyl) diethylene triamine N,N',N''‐tri‐sulfonic acid immobilized on Fe3‐xTixO4 magnetic nanoparticles: A new recyclable heterogeneous nanocatalyst for the synthesis of hexahydroquinolines

“…In continuation of our interest for development of more benign and efficient heterogeneous nanocatalysts and their application in organic transformations and synthesis of various heterocyclic compounds, herein, we were encouraged to prepare the hitherto unreported Fe 3‐x Ti x O 4 bonded N ‐(3‐silyl propyl) diethylene triamine N,N',N'' ‐tri‐sulfonic acid (Fe 3‐x Ti x O 4 @SPDETATSA) nanoparticles (Scheme ), and explore their potential activity as efficient and magnetically recoverable heterogeneous catalyst for the synthesis of hexahydroquinolines (Scheme ).…”

Cu (II)‐β‐cyclodextrin complex stabilized on magnetic nanoparticles: A retrievable hybrid promoter for green synthesis of spiropyrans

“…Some examples of 3,3‐spirooxindole cores with inhibited activity have been presented in Scheme . In recent years, much attention has been focused on catalytic application of magnetic nanoparticles (MNPs) in many organic transformations, including the Häntzch reaction, Biginelli reaction, pyrans, phthalazines, pyrroles and synthesis of spirocompounds . Among the various MNPs, manganese ferrites (MnFe 2 O 4 ) have attracted special interest due to high saturation, low toxicity, good compatibility and super paramagnetic properties .…”

Synthesis and characterization of 4‐AMTT‐Pd(II) complex over Fe3O4@SiO2 as supported nanocatalyst for Suzuki‐Miyaura and Mizoroki‐heck cross‐coupling reactions in water

“…In modern organic synthesis, chemists have concentrated on the magnetic‐based nanocatalysts that are heterogeneous catalysts and have a higher surface area to volume ratio, which raises their selectivity and activity. In addition, these magnetic nanocatalysts permit too easy separation from the reaction admixture through an outer magnet that not only removes the requirement to onerous centrifugation and filtration routes but also decreases energy spending, catalyst waste and preserves time in attaining catalyst reusability …”

“…Fe 3 O 4 (magnetite) has numerous uses in catalysis but, its applications are finite by its propensity to collect around each other, capability to oxidation and low resistance in acidic media. Several policies have been discovered to protect these particles again oxidation and collection of Fe 3 O 4 particles as masses, one of the most encouraging being the utilization of silica as shielding material due to its bio adaptability and inertness, tremendous thermal and mechanical stability and convenient surface area with plenty Si‐OH bonds.…”