Oxalylacetylenes as Dielectrophiles for Annulation of Quinoline Rings: Synthesis of Highly Functionalized 1,3-Oxazinoquinolines

Abstract

Oxalylacetylenes act as dielectrophiles in the annulation of quinolines with highly functionalized 1,3-oxazine cycle decorated by the ethynyl, oxalyl, ester and aryl substituents. The annulation proceeds under mild condition (room temperature, without catalysts) in 2:1 mode with respect to acetylene and quinoline to deliver 1,3-oxazinoquinolines in 45-88% yields. A beneficial feature of the reaction is that, in contrast to results on the reaction of quinolines with trifluoroacetylacetylenes in the presence of water, where H2O acted as a third electrophile, this reaction well tolerates the aqueous medium. This reaction tolerates also isoquinoline and phenanthridine. Received: 02 August 2021 Accepted after revision: 14 September 2021 Publication Date: 14 September 2021 (online) © 2021. Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany