Ultrasound promoted selective synthesis of 2-aryl-5,6-dihydro-4H-1,3-oxazines catalyzed by K-10 and KSF montmorillonite clays: A practical procedure under mild and solvent-free conditions

Abstract

Montmorillonite K-10 and KSF were found to be highly efficient, environmentally friendly and recyclable heterogeneous catalysts for the selective synthesis of a variety of 2-aryl-5,6-dihydro-4H-1,3-oxazines from arylnitriles and 3-amino-1-propanol under ultrasound irradiation. This new methodology provides excellent yields in short reaction times (10-25 min). The reaction work-up is very simple and the catalysts can be easily separated from the reaction mixture and reused several times in subsequent reactions. This catalytic system also exhibits excellent chemoselectivity in the synthesis of mono-oxazines from dinitriles.

Microwave-Assisted Synthesis of 2-Aryl-2-oxazolines, 5,6-Dihydro-4H-1,3-oxazines, and 4,5,6,7-Tetrahydro-1,3-oxazepines

“…Moreover, the presence of this heterocyclic core in many bioactive natural products and chiral catalysts has drawn considerable interest in the development of stereoselective methodologies . One strategy for the synthesis of 2-oxazolines involves the reaction of amino alcohols with carboxylic acids or nitriles in the presence of activating agents or catalysts. , Alternatively, amino alcohols can react with aldehydes in oxidizing media yielding 2-oxazolines . Miscelaneous methods include MCRs, metal-catalyzed reduction of oxazoles, and thionation followed by cyclodesulfurization …”

Ultrasonic oscillations induced property development of water-bentonite suspension containing sulfonated wood coal

“…(4) Natural and modified montmorillonites are high performance catalysts for some organic reactions. Ultrasonic oscillations can provoke the better accessibility of the reactants to catalysts and consequently reduce the reaction time and elevate the yield (Dar et al 2013;Mohammadpoor-Baltork et al 2010).…”