A stereochemical study of cyclopropylcarbinyl derivatives in carbonium-ion reactions

Abstract

Cyclopropylmethylcarbinylamine and cyclopropylmethylcarbinol were resolved and their configurations related. The former was deaminated with aqueous nitrous acid to give the latter with 0-4% net inversion of configuration. The solvolyses of several N-methyl-4-alkoxypyridinium salts were investigated. Solvolysis rates for N-methyl-4- (cyclopropylcarbinyloxy)-pyridinium iodide and perchlorate in water and in 80% ethanol and of N-methyl-4-(cyclopropylmethy1carbinyloxy)-pyridinium iodide in water were measured. The first-order rate constant for the hydrolysis of N-methyl-4-(cyclopropylmethylcarbinyloxy)-pyridinium iodide at 30° was calculated to be 6 x 10^3 times that of N-methyl-4-(cyclopropylcarbinyloxy)-pyridinium iodide. The hydrolysis of optically active N-methyl-4-(cyclopropylmethylcarbinyloxy)-pyridinium iodide produced cyclopropylmethylcarbinol with 4.4 ± 1.5% inversion of configuration. The stereochemistry of the deamination of cyclopropylmethylcarbinylamine and of the hydrolysis of N-methyl-4-(cyclopropylroethylcarbinyloxy)-pyridinium iodide and the ratio of rate constants for the cyclopropylroethylcarbinyl and cyclopropylcarbinyl pyridinium salts are discussed with respect to the possible intervention of non-classical carbonium-ion intermediates in these reactions.