Rhodium-catalyzed regioselective addition of the ortho C–H bond in aromatic amides to the C–C double bond in α,β-unsaturated γ-lactones and dihydrofurans

Abstract

An unprecedented C–H alkylation using α,β-unsaturated γ-lactones (butenolides) and dihydrofurans was achieved by the Rh-catalyzed reaction of benzamides.

The Use of a Rhodium Catalyst/8-Aminoquinoline Directing Group in the C-H Alkylation of Aromatic Amides with Alkenes: Possible Generation of a Carbene Intermediate from an Alkene

“…The reaction of amide 1 (0.3 mmol) with α,β-unsaturated γ-butyrolactone (0.6 mmol) with [RhCl(cod)] 2 (0.0075 mmol) as the catalyst and K 2 HPO 4 (0.075 mmol) as the base in toluene (1 mL) at a temperature of 160°C for 24 h gave the alkylation product 10 in 82% isolated yield (Scheme 14). 39 Curiously, C-C bond formation took place selectively between the ortho carbon atom in 1 and a carbon atom adjacent to the oxygen atom in the γ-lactone ring. This is the first example of the use of α,β-unsaturated γ-butyrolactones in C-H alkylation reactions.…”

“…Various alkenes, such as acrylic esters, 30 styrenes, 38 α,β-unsaturated butyrolactones, 39 dihydrofurans, 39 maleimides, 40 and norbornene derivatives 41 are applicable to the C-H alkylation. The reaction with norbornene results in the formation of unusual endo-hydroarylation products.…”

“…Rhodium complexes were the candidates of choice as catalysts because there are many reactions in which the oxidative addition of C-H bonds is involved as the key step in various C-H alkylation reactions. 4,21,37 As we expected, C-H alkylation reactions with various alkenes, including acrylic esters, 30 styrenes, 38 α,β-unsaturated lactones, 39 dihydrofurans, 39 maleimides, 40 and norbornene derivatives, 41 were achieved when a rhodium catalyst was used in conjunction with an 8-aminoquinoline directing group (Scheme 3). However, the reactions did not proceed via the mechanism as we expected based on the working hypothesis, i.e., hydrometalation or carbometalation which are the generally accepted mechanisms for C-H alkylation with alkenes.…”

Rhodium‐Catalyzed C(sp2)‐ or C(sp3)−H Bond Functionalization Assisted by Removable Directing Groups

“…Bidentate Amide Directing Groups CÀHb ond activation assisted by ab identate directing group is awell-established procedure for the functionalization of amides because of its strong coordination ability towards am etal center.O ne of the most versatile and reliable bidentate directing groups developed to date is the 8-aminoquinoline amide moiety,w hich was introduced by Daugulis and co-workers in 2005 for use in Pd-catalyzed CÀHarylation reactions. [187][188][189][190][191][192][193] In 2014, the Rh I -catalyzed alkylation of 8-aminoquinoline amides was first reported in the reaction of a,b-unsaturated esters (Scheme 53 a). [173][174][175][176][177][178][179][180][181][182][183][184][185][186] Theu tility of an 8aminoquinoline moiety for the Rh-catalyzed functionalization of amides discussed here was mainly reported by Chatani and co-workers in terms of various alkylation and alkenylation reactions.…”

Jenseits von Friedel und Crafts: dirigierte Alkylierung von C‐H‐Bindungen in Arenen

“…Diese Alkylierung wurde später erweitert auf die Verwendung von konjugierten Estern, [90] Styrolen, [91] Dihydrofuranen und ungesättigten g-Lactonen, [92] Maleimiden [93a] und N-Vinylphthalimid [93b] in Gegenwart eines Rhodiumkatalysators.Ein alternatives und recht vielseitiges Katalysesystem auf Basis eines Eisenkatalysators wurde kürzlich von der Gruppe um Ilies und Nakamura verçffentlicht. Es zeigte sich, dass die Selektivitätstark vom Substrat abhing: ortho-Substituierte Amide konnten glatt alkyliert werden, meta-u nd para-s ubstituierte hingegen ergaben wesentliche Mengen an Produkten, die von einer zweifachen Alkylierung in den ortho-u nd ortho'-Positionen herrührten.…”