Synthesis and Investigation of Mass Spectra of 3-[5′-(2′-Substituent)thienyl]benzo[5,6]coumarins

3-5'-(2'-Hydroxycarbonyl)thienyl]benzo5,6]coumarin ( 3 ) was prepared via condensation of 2 with thioglycolic acid in the presence of AcONa and Ac 2 O. Esterification of 3 with alcohols gave 3-5'-(2'-alkoxycarbonyl)thienyl]benzo5,6]-coumarins ( 4a , b ). The chemical behavior of 4 toward nucleophilic reagents (such as ammonia, hydroxyl amine, and hydrazine derivatives) is described. The electron impact ionization mass spectra of compounds 4b , 5 , and 8a , b show a weak molecular ion peak and a base peak of m / z 278 resulting from a cleavage fragmentation. In contrest compounds 3 and 4a show a base peak of m / z 250 and m / z 74 resulting from fragmentation. Compounds 9 and 10 give a characteristic fragmentation pattern with a very stable fragment of m / z 305.