Synthetic experiments in the benzopyrone series

Summary

The initial stages in the synthesis of karanjin have been reinvestigated. A new synthesis of karanjol starting form ψ-resorcylic aldehyde is described. The aldehyde is condensed with bromoacetic ester (1 mol.) in the presence of sodium alcoholate and the product hydrolysed and eventually converted into 4-hydroxy-coumarone by well-known stages. The preparation of karanjic acid from karanjol is male best through the action of sodium methoxide and carbon dioxide. Further stages leading to the synthesis of karanjin have already been described.