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A cesium carbonate (Cs2CO3)-catalyzed [3+3] cycloaddition reaction of coumarin-diazo reagents with glycine imino esters is established to produce tetrahydro-1,2,4-triazines in good yields with excellent regioselectivity. One-pot cycloaddition/oxidation protocol could further provide practical access to a series of new coumarin-decorated 1,2,4-triazines.

A one-pot transformation of α,β-unsaturated trifluoromethyl ketones with 2-(phenylsulfinyl)acetamide to give trifluoromethylated 2-pyridones is realized. The reaction proceeds under mild conditions and involves multiple steps in an expeditious and controlled sequence to provide efficient access to a broad range of trifluoromethylated 2-pyridones in moderate to high yields. Moreover, further synthetic manipulations permit the routine synthesis of a diverse array of trifluoromethylated pyridines with good efficiency.

The diastereoselective carbometalation reaction of cyclopropenyl esters followed by reaction with acylsilanes provides γ-silylated lactones that undergo a ‘sila-Grob’ fragmentation to give pyrone enolates as a new source of acyclic δ-diketones, δ-keto acid, and δ-keto ester derivatives possessing a quaternary stereocenter.