Organoiron complexes in organic synthesis. Part 6. Dienolonium equivalents: tricarbonyl-[1-alkoxy-2-(1–5-η-4-methoxycyclohexa-2,4dienylium)ethane]iron hexafluorophosphates and related complexes leading to masked 4,4-disubstituted cyclohexenones

Abstract

The dienolonium equivalents tricarbonyl-[2-methoxy-1-(1–5-η-4-methoxycyclohexa-2,4-dienylium)ethane]iron hexafluorophosphate (2e) and tricarbonyl-[2-methoxy-1-(1–5-η-4-methoxycyclohexa-2,4-dienylium)propane]iron hexafluorophosphate (2i) react with sodiomalononitrile highly regioselectively to give functionalised gem-disubstituted cyclohexadiene complexes which are potential precursors of 4,4-disubstituted cyclohexenones. The reactions of these and related complexes with other carbanions are also reported.