A Facile Approach to Access Multi‐Substituted Indenes via Nazarov Cyclisation of Aryl, Vinyl, and Alkyl/Aryl Carbinols

Abstract

A divergent approach to highly substituted functionalized indenes has been developed. The two‐step reaction involving nucleophilic addition reaction of aryl vinyl ketone, an ideal intermediate with aryl or alkyl nucleophilic reagent, followed by electrocyclic reaction (Nazarov cyclization) in the presence of Lewis acid catalyst afforded indene derivatives in good to excellent yield.

Brønsted acid-catalysed desilylative heterocyclisation to form substituted furans

“…Modern variations of this process have found different ways of accessing the key pentadienyl cation intermediate, 3 including through dehydration of divinyl alcohols to form substituted cyclopentadienes (Scheme 1a). 4 However, this strategy has rarely been extended to the synthesis of five-membered heterocycles. Würthwein and co-workers reported that α-hydroxy-β,γ-unsaturated oximes undergo dehydration in the presence of stoichiometric triflic acid to form 1-azapentadienyl cations, with subsequent electrocyclisation giving trisubstituted pyrroles.…”