Abstract
2-Carbethoxy-4-hydroxy-5-carbomethoxycoumarone (V) and 2,2-dicarbethoxy-3-hydroxy-6-benzyloxycoumaran (XII) were synthesized respectively from 2,6-dihydroxy-3-carbomethoxybenzaldehyde (IV) or 4-benzyloxy-2-hydroxybenzaldehyde (X) and ethyl bromomalonate by the method of Tanaka for benzofuran synthesis. 2-Carbethoxy-4-hydroxy-5-carbomethoxycoumarone (V) was hydrolysed to 4-hydroxycoumarone-2,5-dicarboxylic acid (VI). This dibasic acid VI was decarboxylated in quinoline with copper powder into a mixture of karanjol (VIII) and karanjic acid (IX). 2,2-Dicarbethoxy-3-hydroxy-6-benzyloxy-coumaran (XII) was hydrolysed to 6-benzyloxycoumarone-2-carboxylic acid (XIII).