Palladium incorporated on magnetic hybrid nano hydroxyapatite as an Effectiveheterogeneous catalyst for the Preparation of propargylamines via One-pot andthree-component reaction in green Media

Nano-hydroxyapatite (n-HA) with the chemical formula Ca۱۰(PO۴)۶(OH)۲ has established significantattention as an graft compounds because of its great biocompatibility in the health care industry. Importantly, mineralphases and chemicals of n-HA are similar to structure of bones that its application in the field of orthopedics anddentistry has been investigated. In recent years, n-HA have been extensively used as catalysts, biomaterials, ionicexchangers, luminescent materials and oxide ion conductors because of their unique properties [۱]. Many syntheticmethods have been developed to generate these compounds as catalysts in some organic transformations.However, the promotion of new methods for improving catalytic activity of hydroxyapatite with different structures isneeded. Three-component reaction of terminal alkynes, amines and aldehydes, A۳-coupling reaction, is wellestablishedprotocol for the synthesis of a class of key synthetic intermediates, propargylamines [۲]. Thesechemicals have broad range of applications for the synthesis of various natural and biologically active chemicals[۳]. A۳-coupling reaction is a catalytic process and can be promoted by using various catalysts such as palladium,silver, copper, iron, gold, and nickel based catalysts [۲]. The main drawbacks of these materials is that they arehomogeneous and also difficult to recover.Hence, disclosing new an effective and recyclable catalysts has attractedintensive attention. In the following of our attempt to introduce heterogeneous and recoverable catalysts orpromoting different organic reactions and developing eco-freindly methods for effective synthesis of chemicals, [۴-۶] herein we report the new method for the one-pot synthesis of propargylamines catalyzed by palladated magneticnanohydroxyapatite as a heterogeneous catalyst. The magnetic Pd@n-Ha-ASAM was synthesized through multistepprocedure. To this propose, n-HA was substituted with (۳-aminopropyl) trimethoxysilan and subsequentlytreated with acrylamide and ۵-sulfosalicylic acid. On the other hand, Fe۳O۴ NPs was prepared and functionalizedwith melamine and then hybridized with that of functionalized-n-Ha, which could serve as an effective support forimmobilization of Pd species. Next, the catalytic activity of magnetic Pd@n-Ha-ASAM was evaluated in the synthesisof propargylamines via three-component reaction of amine, phenyl acetylene and aromatic aldehydes involvingelectron-withdrawing or -donating substituents in H۲O as solvent. The remarkable merits of this strategy are highyields (۸۵-۹۹%) of the expected products and easy workup procedure. Notably, the nanocatalyst was readilyrecovered, and reused several times without significant decrease in the yield of the product of model reaction.

Keywords:

Heterogeneous Catalyst , Nano Hydroxyapatite , A۳ -coupling reaction