TRIS(1-NAPHTHYL)-METHYL AND TRIS(2-NAPHTHYL)METHYL CATIONS - HIGHLY CROWDED TRIARYLMETHYL CATIONS

The highly hindered tris(1-naphthyl)methyl and tris(2-naphthyl)methyl cations 3 and 5 have been prepared under long lived stable ion conditi ons and characterized by C-13 NMR Spectroscopy at low temperatures. Th e latter can abstract hydride from cycloheptatriene to afford tris(2-n aphthyl)methane 7, but the reaction of cycloheptatriene with the more crowded cation 3 failed to give the corresponding hydrocarbon. A prima ry kinetic isotope effect. k(H)/k(D) = 7.1 +/- 0.5, found in the forme r case supports a colinear hydride abstraction mechanism. The ions 3 a nd 5 upon quenching rearranged to give a mixture of isomeric 13-(1-nap hthyl)-1,2,7,8-dibenzofluorene 4 and 13-(2-naphthyl)-2,3,6,7-dibenzofl uorene 6, respectively.