In the Pechmann reaction with malic acid, m-cresol and 3, 4-xylenol give mixtures of alkylcoumarins containing about 10% of the 5-and 5, 6-isomers respectively. 7- Alkylcoumarins only are obtained from the reaction with ethylacetoacetate. A study of ortho- proximity effects on the 13C NMR of dimethylcoumarins is reported, and the results have been correlated with similar effects in other aromatic and heteroaromatic systems.
