2,2,4,4-tetramethyl-5',5'-diphenylspiro[cyclobutane-3,4'-[1,3]dithiolane]-1-one

1,1,3,3-tetramethyl-6,6-diphenyl-5,8-dithiaspiro[3.4]octan-2-one

l-thiofenchone

4,4-bis(4-methoxyphenyl)-5,5-diphenyl-1,3-dithiolane

5,5-diphenylspiro[1,3-dithiolane-4,9'-thioxanthene]