Highly regioselective ferrocenyl cyclohexene/cyclopentene isomerization through benzyne transfer coupling

Abstract

Highly regioselective ferrocenyl cyclohexene/cyclopentene isomerization through hexadehydro-Diels–Alder (HDDA) benzyne transfer coupling is developed. The tetraynes result in the formation of an aryne through the HDDA reaction which is then in situ trapped by ferrocene-tethered cyclohexene/cyclopentene under mild conditions without a catalyst. The density functional theory (DFT) calculations reveal that the Alder-ene reaction process is the key to obtaining functionalized ferrocene derivatives with high regioselectivity and excellent yields by a 1,3-transposition of the involved alkenes. This work expands the coupling reaction between arynes and cyclic alkenes, further providing an innovative approach for the synthesis of ferrocene derivatives.