13C-1H Coupling Constants in Carbocations. 8. Application of the ΔJ Equation o Tertiary Dicyclopropylcarbinyl Cations: The Methyl Dicyclopropylcarbinyl, (1α,3β,5β,7α)-2-Methyltricyclo3,5>octan-2-yl, (1α,3α,5α,7α)-2-Methyltricyclo3,5>octan-2-yl, and 3-Methy...

Article abstract of DOI:10.1021/jo00111a025

One-bond 13C-1H coupling constants have been determined for the title cations (10,15,20, and 25) in superacids and the values for the carbons adjacent (α) to the cationic centers compared with those of the appropriate model ketones to obtain the ΔJ values.These values were found to be in the range 10-15 Hz, approximately one half that expected for a single cyclopropylcarbinyl cation.This has been interpreted in terms of delocalization of charge into the second cyclopropyl group in those cations which can adopt double bisected conformers, 10, 20, 25, and in terms of averaging of the coupling constants as a result of two different dihedral angles in cation 15.New method for the synthesis of precursors to the 2-methyltricyclo<5.1.0.0^3,5>octan-2-yl cations, 15 and 20, have been developed.