A mild and efficient synthesis of substituted quinolines via a cross-dehydrogenative coupling of (bio)available alcohols and aminoarenes

A ruthenium-catalysed dehy drogenativecross-coupling of primary alcohols and imines inthe presence of TFA provided a library of different-ly substituted quinolines. Imines can be prepared insitu from various anilines and several benzyl alco-hols using a ruthenium-catalysed hydrogen-transferprocedure. Without changing the catalyst, quino-lines can be obtained in moderate to good yields byadding various primary alcohols in the presence ofTFA (30 mol%) via a “telescopic” protocol. Theuse of alcohols, the absence of strong oxidants andthe diversity of potential starting materials makethis modern version of the Skraup reaction superi orto most of the conventional quinoline syntheses.