Beschreibung:
<jats:p> The double addition of bis(trimethylsilyl) ketene acetals (1a–1b, R<jats:sub>1</jats:sub> = CH<jats:sub>3</jats:sub>, –(CH<jats:sub>2</jats:sub>)<jats:sub>5</jats:sub>–) to 2-substituted pyrazines promoted by triflic anhydride leads to γ-lactones in a single step. A systematic study involving electron-withdrawing and electron-donating groups (R<jats:sub>2</jats:sub> = CN, COOMe, PhCH=CH, Cl, Me, OMe) in the pyrazine ring reveals a strong dependence of electronic effects on the regiochemistry of nucleophilic addition. </jats:p>