Solvolytic and Stable Ion Studies of 1,1'-Diadamantylmethyl Cations

Article abstract of DOI:10.1021/jo00345a029

A series of 1,1'-diadamantylmethyl carbocation systems were studied under solvolytic and stable ion conditions.At low temperatures in superacid solutions, tertiary 1,1'-diadamantylmethyl derivatives (except tert-butyl-1,1'-diadamantylmethyl) gave the corresponding static carbenium ions.From the 1H and 13C NMR spectroscopic data, the ion from secondary 1,1'-diadamantylmethyl precursors is assigned the rearranged 4-(1-adamantyl)-3-homoadamantyl cation structure.However, this species is not static but undergoes fast Wagner-Meerwein shifts even at very low temperatures(ca. -140 deg C) to give a set of six equivalent carbenium ions.There is no evidence for bridging.In solvolysis, the relatively low α-CH3/H rate ratios of the 1,1'-diadamantylmethyl and di-tert-butylmethyl systems strongly suggest that both secondary substrates undergo anchimerically assisted ionization of modest magnitude.