Construction of polycyclic bridged indene derivatives by a tandem 1,3-rearrangement/intramolecular Friedel–Crafts cyclization of propargyl acetates

Abstract

An unprecedented Lewis acid-catalyzed cascade 1,3-rearrangement/Friedel–Crafts cyclization of propargyl acetates is developed for the construction of polycyclic bridged indene derivatives.

Cooperative Catalysis for the Highly Diastereo‐ and Enantioselective [4+3]‐Cycloannulation of ortho‐Quinone Methides and Carbonyl Ylides

“…[2] However, there still remains a high demand for the synthesis of oxa-bridged heterocycles. [3] The combination of a transition-metal catalyst and a Lewis acid or organocatalyst to activate two different substrates for a given reaction has attracted significant interest among synthetic organic chemists recently since it potentially enables highly efficient and/or unprecedented complex chemical transformations in a one-pot operation. [4] The success of this strategy relies upon the simultaneous activation of two reacting partners by two different catalysts that operate in concert in two distinct catalytic cycles.…”

Substrate‐Controlled Product Divergence in Iron(III)‐Catalyzed Reactions of Propargylic Alcohols: Easy Access to Spiro‐indenyl 1,4‐Benzoxazines and 2‐(2,2‐Diarylvinyl)quinoxalines

“…At first, the alcohol group of the substrate 1/2 is activated (species A ) through co‐ordination with Fe III ‐catalyst leading to the generation of a transient propargylic carbocation B [20a] . Next, species B undergoes intramolecular nucleophilic attack by the tethered NHTs group to generate an allenic intermediate 3’ (X=O)/ 4’ (X=NTs) [21a] which forms a complex [20b–c,21b] with FeCl 3 (species C ) to give rise to the product [22] 3 / 4 following pathway I or II as described below.…”