Acid-Promoted One-Pot Synthesis of Substituted Furan and 6‑Methylpyrazin-2(1<i>H</i>)‑one Derivatives via Allene Intermediate Formed in Situ

Under the acidic conditions, substituted furans were constructed from γ-alkynyl ketones through corresponding allene intermediates in one-pot. The methodology was also tailored to a series of the Ugi reaction products for the synthesis of 6-methylpyrazin-2­(1H)-one derivatives. The current method offered significant advantages for the combinatorial applications of these chemical scaffolds.