Catalytic generation of ortho-quinone dimethides via donor/donor rhodium carbenes

Abstract

Substrates engineered to undergo a 1,4-C–H insertion to yield benzocyclobutenes resulted in a novel elimination reaction to yield ortho-quinone dimethide (o-QDM) products that undergo Diels-Alder or hetero-Diels-Alder cycloadditions. The analogous...

Quantum Chemical Interrogation of Reactions Promoted by Dirhodium Tetracarboxylate Catalysts─Mechanism, Selectivity, and Nonstatistical Dynamic Effects

“…In a study with the Tambar group involving the oxonium ylide shown, we again predicted a preference for [Rh]-free rearrangement, and again no competing [Rh]-bound transition structure was found. Finally, in another study with the Shaw group, we predicted [Rh]-free [4 + 2] cycloaddition. Note that the ylide in this case can also be formulated as an ortho -quinodimethide.…”

Sultines as o-Quinodimethane Precursors in an Oxa-Diels–Alder Reaction: Synthesis of Functionalized Isochromans

“…16b More recently, the Shaw group reported the catalytic formation of o -QDMs from rhodium carbene intermediates, with subsequent interception of the o -QDMs by various dienophiles (Scheme 1c ). 16c In the context of sultines as o -QDM precursors, the reactivity of sultines with glyoxylates in an oxa-DA reaction has been reported only as part of a synthetic effort toward heteroanthracycline antitumor drugs. 17 An exceedingly high equivalence of oxa-dienophiles was required to obtain synthetically useful yields of isochromans.…”