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.

Catalyst-free nucleophilic substitution of hydrogen in quinoline rings by acylethynylpyrroles: stereoselective synthesis of 2-(E-2-acylethenylpyrrolyl)quinolines

“…Commercial samples of quinolines 1a–g , phenanthridine 4 and 1-methylisoquinoline 6 were used. Acylethynylpyrroles 2a–h , 19 6-methoxyquinoline 1f 35 and ( E )-1-phenyl- N -(quinolin-5-yl)methanimine 1h 36 were obtained according to the literature procedures. The products 3a–q, 5a,b and 7 were purified by column chromatography.…”

Recent Strategies in the Nucleophilic Dearomatization of Pyridines, Quinolines, and Isoquinolines

“…The reaction took place at room temperature with two molecules of acetylene, to render densely functionalized tetrahydropyrido­[2,1- b ]­[1,3]­oxazines 201 as mixtures of diasteroisomers in moderate to good yields. The process was further extended to quinolines with comparable results …”

“…The process was further extended to quinolines with comparable results. 152 Cao, Zhang, and co-workers evaluated the three-component domino reaction of quinolines 2, methyl perfluoroalkyl-2ynoates 192 and isatin derivatives 90, for the synthesis of perfluoroalkyl-substituted spiro-1,3-oxazines 202, which were obtained as almost equimolecular mixtures of diasteroisomers (Scheme 100, eq 1). 153 This reaction proceeded via an intermolecular Michael addition of the quinoline ring to the more electrophilic carbon center of the triple bond to generate a Huisgen's 1,4-dipole intermediate, which evolved through nucleophilic addition to the carbonyl group of isatin and cyclization.…”