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

An ultrasound assisted efficient, expeditious and environmentally benign new methodology for direct access to broad ranges of structurally interesting and pharmacologically significant spiropyrido[2,1-b][1,3]oxazino compounds based on three component reactions approach via domino 1,4-dipolar cycloaddition from easily available starting materials in aq. ethanol medium at room temperature (25-30 degrees 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 methodology leads to the reduction of the reaction times.

Automated summary

A new ultrasound-assisted method has been developed for the direct access to spiropyrido[2,1-b][1,3]oxazino compounds, which are structurally interesting and pharmacologically significant, via a three-component reaction approach. This method offers simple experimental and workup procedures, excellent yields, good functional group tolerance, cleaner reaction profiles, and the use of green solvents as remarkable features. Moreover, the use of ultrasound in this methodology leads to reduced reaction times.