Synthesis and Mass Spectral Fragmentation of A Series of Substituted Coumarins and Their Fused Derivatives

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The reaction of thiourea with 3-ethoxycarbonyl coumarin (1) and 3-chlorocoumarin (7) in the presence of potassium carbonate in water gave substituted coumarins 4 and 8. The reaction of thiourea or thiosemicarbazide with 1 and 7 in the presence of potassium carbonate in methanol yielded the corresponding fused coumarins 5, 9 and 10. EI mass spectrometric behaviour of compounds 4, 8 and 9 show a strong molecular ion peak and a base peak of m/z 146, m/z 89 and m/z 150 resulting from a cleavage fragmentation, respectively. The molecular ion of compounds 5 and 10 is a base peak of m/z 246 and m/z 235, respectively.

Thiourea; Substituted coumarins; Mass spectral fragmentation