Development of a new method for the synthesis of benzo[h][1,6]naphthyridine derivatives and chromenopyrazinone skeleton

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2015
Hoplamaz, Emre
In the first part of this thesis, a new methodology was developed for the synthesis of benzo[h][1,6]naphthyridine derivatives. Firstly, 2-(diprop-2-ynylamino)benzaldehyde was synthesized starting from 2-aminobenzoic acid in three steps. Then, cyclization reaction was achieved in the presence of propargyl amine and DBU. The expected 3-methylbenzo[h][1,6]naphthyridine was obtained. To generalize this methodology, several derivatives of 2-(diprop-2-ynylamino)benzaldehyde were synthesized by applying Sonogashira coupling reaction in good yields. Cyclization reaction of these derivatives were succeeded by using propargyl amine and DBU. Finally, aryl and methyl substituted benzo[h][1,6]naphthyridine derivatives were obtained in good yields. In the second part, a new synthetic method for the synthesis of a chromenopyrazine and a chromenopyrazinone derivative was developed. Firstly, acetonitrile group was introduced to salicylaldehyde. Then, reaction of this aldehyde with propargyl amine gave imine. DBU-supported cyclization reaction afforded the product, 3-methyl-5H-chromeno[3,4-b]pyrazine. Finally, cyclization product was oxidized with CrO3/pyridine to yield 3-methyl-5H-chromeno[3,4-b]pyrazin-5-one. In order to generalize this reaction, two different aldehyde substituted at the benzene ring were employed. Same procedure for cyclization reaction was applied to get chromenopyrazine derivatives. Unfortunately, expected chromenopyrazine and chromenopyrazinone derivatives were not obtained.
Citation Formats
E. Hoplamaz, “Development of a new method for the synthesis of benzo[h][1,6]naphthyridine derivatives and chromenopyrazinone skeleton,” M.S. - Master of Science, Middle East Technical University, 2015.