Ultrasound-Assisted Expeditious Catalyst-Free Green Approach towards Diastereoselective Synthesis of Spiro [indoline-3,2’-pyrido[2,1-b][1,3]oxazine]-3’,4’-dicarboxylate Scaffolds

摘要

An ultrasound assisted efficient, expeditious and environ- mentally benign new methodology for direct access to broad ranges of structurally interesting and pharmacologically signifi- cant spiropyrido[2,1-b][1,3]oxazino compounds based on three component reactions approach via domino 1,4-dipolar cyclo- addition from easily available starting materials in aq. ethanol medium at room temperature (25-30°C) has been developed. In comparison to that of conventional methods, simple experimental and workup procedure, excellent yields, good functional group tolerance, cleaner reaction profile, use of green solvent are remarkable features of this sonochemical procedure.Furthermore, using of the ultrasound in this method- ology leads to the reduction of the reaction times.