Mild Rhodium(III)‐Catalyzed CH Activation and Intermolecular Annulation with Allenes

Abstract

All(enes) great! A novel Rh(III)-catalyzed oxidative coupling with allenes under mild conditions provides heterocycles with exocyclic double bonds. This reaction features low catalyst loadings, high regio- and stereoselectivity, and excellent substrate scope. The products were derivatized and preliminary mechanistic studies were conducted.

Synthesis of Isoquinolinones via Regioselective Palladium-Catalyzed C–H Activation/Annulation

“…The structure of 3 was determined and confirmed by 2D NMR experiment (NOESY) (3g) and X-ray analysis (3i) (see Supplementary Materials). Consistent with what is reported in the literature [56], the reaction was highly regioselective with regard to the insertion of allene into the palladium complex. The nucleophilic addition or reductive elimination occurred at C4 of 2,3-allenoic acid esters.…”

“…At the outset of this work, the reaction between N-methoxybenzamide 1a and 2,3-allenoic acid esters 2a was initially examined under the reaction conditions reported by Glorius in their work [56], Scheme 1. Syntheses of isoquinolinone via metal-catalyzed oxidative annulation of allenes.…”

“…At the outset of this work, the reaction between N-methoxybenzamide 1a and 2,3-allenoic acid esters 2a was initially examined under the reaction conditions reported by Glorius in their work [56], which used [{RhCp*Cl 2 } 2 ] as catalyst and CsOAc as additive. However, no desired product was observed when the reaction was performed in methanol at room temperature.…”

“…The initial effort in this area, reported by Ma [55], resulted in a direct allenylation reaction with N-methoxybenzamide. In 2012, Glorius and co-workers [56] reported the synthesis of hydroisoquinolinones from the first carbometalation reaction of allenes; however, the applicable substrates were limited to alkyl substituted allenes (Scheme 1a). In 2014, the synthesis of 3,4-dihydroisoquinolin-1(2H)-ones was successfully achieved by Liang [57], using strong NH acidic Nbenzoylsulfonamide to react with allenes in a palladium-catalyzed activation/annulation (Scheme 1b).…”

A facile palladium catalysed 3-component cascade route to functionalised isoquinolinones and isoquinolines

“…6 Recently, Glorius et al, employed Rh(III) to catalyse C-H activation of N-(pivaloyloxy)benzamide involving 35 intermolecular annulation with substituted allenes to furnish isoquinoline-1(2H)-ones. 7 As part of our program of research into the development and application of palladium catalysed allene insertion cascades, we have previously reported a number of examples of three-40 component cascades for the synthesis of N-substituted 4-methylene-3,4-dihydro-1(2H)-isoquinolinones. A feature of these reactions is that, following an initial Pd-mediated intramolecular allene insertion, both intra-and intermolecular nucleophilic addition then occurs to give tetra-fused ring systems containing 45 an isoquinolinone ring.…”