A novel synthesis of chromone based unnatural $$\upalpha $$ α -amino acid derivatives

Abstract

An efficient method for the preparation of chromone based α-amino acid derivatives by alkylation of glycinate schiff base with 3-bromomethyl chromone as well as 2-bromomethyl chromone has been described. Using this method, 2-amino-3-(4-oxo-2-chromenyl)propanoic acid and 2-amino-3-(4-oxo-3chromenyl)propanoic acid, two novel chromone-amino acid conjugates have been prepared. Furthermore, the separation of chromone amino acid enantiomers by chiral column chromatography was accomplished.

Recent advances in the synthesis of 4H-chromen-4-ones (2012 − 2021)

“…Diversely substituted ethyl 4-oxo-4H-chromene-2-carboxylates result from condensation reaction of 2 0 -hydroxyacetophenones with diethyl oxalate carried out in the presence of sodium ethoxide in ethanol at 60 °C for 16 h, 170 100 °C for 10 h 145 or refluxing conditions during 1h, 171,172 2h, 173 10 h 174,175 or 12 h. 176 Subsequent intramolecular cyclization reaction in acidic medium completes the process to give the desired carboxylates. Further derivatives were obtained from the reaction of 2 0 -hydroxyacetophenones with diethyl oxalate in the presence of sodium hydride in THF at room temperature overnight followed by treatment with diluted hydrochloric acid (Scheme 19).…”

“…255,[310][311][312][313] More examples were obtained from the reaction of 2 0 -hydroxyacetophenones with oxalyl chloride in DMF at room temperature, in good yields. 170 Scheme 41…”