Action of Grignard reagents on thiophthalic anhydride, 3-benzal-2-thiophthalide, 3-p-chloro- and 3-p-methoxybenzalphthalides

Thiophthalic anhydride 1 reacts with the GRIGNARD reagents 2a – e (1:1 mol.) to give the corresponding 3-aryl(alkyl)-3-hydroxy-2-thiophthalides 3a – e . The interaction of 1 with 2c and f (1:2 mol.) yields the corresponding 1,2-diaroylbenzene derivatives 4 . On the other hand, 1 reacts with 2b (1:2 and 1:3 mol.) to give 5 and 6 , respectively. When 3-benzal-2-thiophthalide 7a and 3-p-chlorobenzalphthalide 7b are allowed to react with the GRIGNARD reagents 2c – f , the corresponding indenone derivatives 8 are obtained. On the other hand, the reaction of 7a and b with 2b (1:2 mol.) yields 6 and 9 , respectively. 7a and p-methoxybenzalphthalide 7c react with 2b (1:1 mol.) to give 5 and 10 ( a and b ). The constitution of the products has been investigated by means of IR and UV spectra.