Synthetic experiments in the benzo-pyrone series. Part I. Synthesis of karanjin-α-carboxylic acid

Abstract

2-Methyl-3-methoxy-7-hydroxychromone-8-aldehyde formed a sodium derivative which readily condensed with bromoacetic ester to form the corresponding carbethoxy-methyl ether. This reaction did not take place satisfactorily with 3-methoxy-7-hydroxyflavone-aldehyde. The condensation was, however, smoothly effected in boiling benzene solution in the presence of potassium carbonate. When hydrolysed with aqueous potassium hydroxide, simultaneous ring-closure took place to yield 3-methoxyflavono-7:8-furan-α-carboxylic acid which is considered to be karanjin-α-carboxylic acid.