... Volume: Page: ... When a p-xylene solution of 1a was refluxed for 3 days, 68% of 1a was consumed and 2,4-diphenyl thiophene (4), 13 1,3-dihydro-2-benzothiepin 5, and 1,2-bis( methylthiobenzylidene)cyclobutane 6 were obtained in 30, 18, and 8% yields ...