CHEMICAL CONSEQUENCES OF LONG-RANGE ORBITAL INTERACTIONS IN NORBORNANE-L,4-DIOL MONOSULFONATE ESTERS

Seven monotosylated 1,4-diols with the rigid norbornane skeleton were treated with a strong base in refluxing benzene to find out whether th ese compounds react by initial heterolysis of the tosylate ester bond induced by long-range orbital interactions. The tosylates 1-7 were des igned to investigate the influence of the sigma-relay (U-, sickle-, or W-shaped) between the donor and acceptor end of the system, to check whether primary carbocationic ion pairs could act as intermediates, an d to study conformational influences on reactivity and product formati on. Tosylate 1 with a U-like arrangement of the sigma-relay reacted re latively slowly and followed reaction pathways in which no long-range orbital interactions are involved. The reaction outcome of tosylate 2 which possesses a sickle-like arrangement of the sigma-relay indicates two competitive processes with and without the involvement of long-ra nge orbital interactions. The secondary tosylates 3, 6, and 7 which al l possess a W-like arrangement reacted relatively fast and showed pred ominantly homofragmentation. Although an ideal W-like arrangement is p resent in the primary tosylates 4 and 5, no reactions in which long-ra nge orbital interactions are involved were observed. The tosylates 6 a nd 7 in which the tosylate group is conformationally mobile can give r ise to mixtures of products. The ratio in which these products are for med can be rationalized by using the Curtin-Hammett principle.