MEDIUM-SIZED CYCLOPHANES .29. SYNTHESIS AND DESULFURIZATION OF 2,11-DITHIA[3]METACYCLO[3](4,9)PYRENOPHANES AND 2,11-DITHIA[3]PARACYCLO[3](4,9)PYRENOPHANES

2,11-Dithia[3]metacyclo- (14b) and 2,11-dithia[3]paracyclo[3](4,9)pyre nophane (14c) were obtained by the coupling reactions of 4,9-bis(chlor omethyl)pyrene (12) with the corresponding bis(mercaptomethyl)benzenes (13b, c). Attempted pyrolysis of the disulfones 18b, 18c to afford [2 ]metacyclo- (19b) and [2]paracyclo[2](4,9)pyrenophane (19c) failed. On ly the ring cleavage products 16 and 20 were obtained. The sulfur diox ide extrusion by vapor-phase pyrolysis of the corresponding disulfone 18 to the highly strained 19 clearly demonstrates the limits of these preparative ring contraction method. The photolytic desulfurization of 14c afforded the [2](1,5)naphthaleno[2]paracyclophane analogue 21 ins tead of [2]paracyclo[1](4,9)pyrenophane 21'. The mechanism of the pyro lysis and photolysis reactions is discussed.