Remote Friedel–Crafts Reaction with α-Heteroaryl-Substituted Cyclic Ketones via HOMO Activation of Lewis Bases

Abstract

Under the catalysis of Lewis bases, cyclic enones bearing an α-(2-furyl) motif can undergo remote Friedel–Crafts reaction with electrophilic reagents via a HOMO-activation strategy, proceeding in a formal vinylogous Rauhut–Currier or Morita–Baylis–Hillman-type reaction pattern. Moreover, even less reactive α-(2-benzofuranyl)-substituted cyclopeten-2-ones can be similarly HOMO-raised and furnish [4 + 2] products with alkylidenemalononitriles in a cascade Friedel–Crafts/Michael addition process.

Highly regioselective synthesis of lactamsviacascade reaction of α,β-unsaturated ketones, ketoamides, and DBU as a catalyst

“…36 Subsequently, regioselective Michael addition between β-substituted-cyclohexenones and nitroalkenes was explored. 32 In addition, some bifunctionalizations to obtain cycloadducts were reported by Chen and Jørgensen et al from the α′,γ-positions, 37 α′,γ′-positions, 23 β,γ-positions, 38–43 γ,γ′-positions 44 and others 45–47 in cascade reaction of α,β-unsaturated ketones. In spite of many catalytic methodologies available for the functionalization of α,β-unsaturated ketones at their α, α′, β, γ, γ′ positions and multiple reaction sites with a variety of substrates.…”

Chemoselective tandem SN2′/SN2′′/inter- or intramolecular Diels–Alder reaction of γ-vinyl MBH carbonates with phenols and o-hydroxychalcones

“…Inspired by elegant works utilizing vinylogous electron-deficient allenes 6 or alkenes 7 in the filed of nucleophilic organophosphine catalysis, we speculated that the MBH adducts bearing a γ-vinyl group would easily undergo an S N 2′ addition to give a conjugate diene intermediate, thus enabling an opportunity to unlock new reaction pattern rather than well-established S N 2′ or S N 2′/S N 2′ reaction (Scheme 1b). Noteworthy is that allylic alkylations of phenol pronucleophiles with γ-vinyl MBH adducts have been reported, in which the vinyl moiety remained inert in the reaction.…”