Cobalt ferrite nanoparticles: a magnetically separable and reusable catalyst for Petasis-Borono–Mannich reaction

Abstract

Magnetically separable cobalt ferrite nanoparticles (CoFe 2 O 4 , NPS) have been demonstrated for the first time as an efficient catalyst in Petasis-Borono-Mannich (PBM) reaction between salicylaldehydes, sec.amines and aryl boronic acids to furnish alkylaminophenols in high yields. Relatively shorter reaction times, easy purification of the products and reusability of the catalyst for five consecutive runs without appreciable loss in it's activity are the noteworthy features of the developed protocol.a Reaction conditions: salicylaldehyde (1 mmol), piperidine (1.2 mmol), phenyl boronic acid (1.2 mmol), acetonitrile (5 mL), catalyst. b Isolated yield. c Using water (5 mL) as the reaction medium.This journal is

Reactivity and Synthetic Applications of Multicomponent Petasis Reactions

“…This common product may be synthesized via PRs under a variety of conditions. 76−79 The addition of molecular sieves (MSs) to remove water usually accelerates this PR variant, 80−82 although PRs are reported to be water-compatible. 83−85 Water removal from the reaction mixture presumably drives the equilibrium from a hemiaminal species formed between aldehyde and amine components to a synthetically active iminium species.…”

“…Tertiary phenolamines of general structure 28 can be obtained through PRs involving salicylaldehyde. This common product may be synthesized via PRs under a variety of conditions. − The addition of molecular sieves (MSs) to remove water usually accelerates this PR variant, − although PRs are reported to be water-compatible. − Water removal from the reaction mixture presumably drives the equilibrium from a hemiaminal species formed between aldehyde and amine components to a synthetically active iminium species. A PR of salicylaldehyde derivatives was performed in the presence of MS, which made it possible to perform the reaction under milder conditions at room temperature and to eliminate side products.…”

“…87 Alkylaminophenols with core scaffold 28 could also be generated through cobalt ferrite nanoparticle-catalyzed PRs. 76 Another series of similar diphenylmethanamines, generally containing a morpholino instead of a pyrrolidino alkyl moiety, was synthesized using a catalysis based on chitosan or trititanate nanotubes in high yield. The methodology could also be extended to a series of piperazine-substituted aminophenols.…”

Multicomponent Mannich‐Like Reactions of Organometallic Species

“…In the past few years, further insights into the reaction mechanism have been disclosed, as well as the implementation of alternative conditions such as reactions in water or under solvent‐free conditions in thermal or microwave‐assisted procedures . Several catalysts such as molecular sieves, chitosan, cobalt ferrite nanoparticles, and H 2 Ti 3 O 7 nanotubes have also been assessed in the process. Asymmetric versions of the reaction have also been investigated.…”

Bentonite ‐ Clay ‐ Supported Cuprous Iodide Nanoparticles (BENT‐ CuI NPs): A New Heterogeneous Catalyst in Diversity ‐ Oriented Synthesis of 1, 2, 3‐ Triazoles in Aqueous Medium

“…On the other hand, as far as in situ generation of azides is concerned organic halides, epoxides, as well as arylboronic acids have been widely used as azide precursors . Literature pursuance interestingly revealed that, in most of the earlier reports the synthesis 1, 2, 3 ‐triazoles has been achieved using any one of the aforementioned precursors and to the best of our knowledge there are only two reports wherein the synthesis of triazoles has been achieved using all the aforementioned azide precursors Taking recourse to this literature survey and our continued interest in heterogeneous catalysis, we decided to design a novel heterogeneous catalyst and to explore the same in the synthesis of 1,2,3‐triazoles using organic halides, epoxides, as well as arylboronic acids as azide precursors. In this communication we report Bentonite clay supported CuI nanoparticles (BENT CuI‐NPs) as a novel heterogeneous catalyst in diversity oriented synthesis of 1, 2, 3‐triazoles ( Scheme ) .…”