Base-promoted tandem ring-opening/ring-closing of N-alkynyl-2-oxazolidinones enables facile synthesis of 2-oxazolines.

A K₂CO₃-promoted tandem ring-opening/ring-closing of N-alkynyl-2-oxazolidinones has been described, affording 2-oxazolines in 42-99% yields without column chromatography isolation. This operationally simple reaction proceeds under ambient conditions without a transition-metal catalyst and an external oxidant and can be applied for the late-stage functionalization of biologically active compounds.