The photochemicalreaction of a series of 2-aryl-1,2-benzisothiazol-3(2H)-ones (1) under deaerated conditions was found to give dibenzo[b,f][1,4]thiazepin-11(10H)-ones (2). A mechanism through a biradical species is proposed for the photoreaction. When the photolysis of 1 was carried out in the presence of oxygen, 2-aryl-1,2-benzisothiazol-3(2H)-one 1-oxides (11) were formed together with compounds
Arylthiol and dithiobisarylamide antibacterial and antiviral agents have the general formula ##STR1## where A is monocyclic or bicyclic aryl which can contain up to 3 heteroatoms selected from O, S, and N, R.sup.1 and R.sup.2 are substituent groups, X is ##STR2## or SO.sub.2 NR.sup.4 Z, Y is H or SZ when n is 1, a single bond when n is 2; R.sup.4 and Z can be hydrogen or alkyl.