Experimental and theoretical studies of the [3,3]-sigmatropic rearrangement of prenyl azides

Abstract

[3,3]-Sigmatropic rearrangement of isoprenyl azides has been extensively investigated in an experimental and theoretical level. Prenylazides with different chain lengths and phenyl prenylazide have been synthesized. NMR analysis of each azide has been made to determine the equilibrium composition, showing the predominance of primary allyl azides over the tertiary ones and E over Z isomer, regardless of the chain length, temperature, solvent or the regiochemistry of the precursor isoprenyl alcohol. It was determined that phenyl prenylazides do not experience [3,3]-sigmatropic rearrangement. In order to rationalize the experimental results and to gain insight in the mechanism of the [3,3]-sigmatropic rearrangement of prenylazides a theoretical study was performed using density functional theory and the QTAIM approach.