Practical Pd(II)-Catalyzed C–H Alkylation with Epoxides: One-Step Syntheses of 3,4-Dihydroisocoumarins

Abstract

Pd(II)-catalyzed ortho-alkylation of benzoic acids with both terminal and internal epoxides affords 3,4-dihydroisocoumarins in one step. The presence of potassium countercations is crucial for this reaction. Monoprotected amino acid ligands significantly promote this reaction, enabling the development of a practical C-H alkylation reaction using 0.5 mol % Pd catalyst. The inversion of stereochemistry in the C-H alkylation step is consistent with a redox-neutral SN2 nucleophilic ring-opening process as opposed to a Pd(II)/Pd(IV) pathway.

Increasing Catalyst Efficiency in C−H Activation Catalysis

“…[37a,b] Thus,u sing 0.2 mol %o fP d(OAc) 2 and 0.4 mol %o fN-acetyl isoleucine,t he olefination of as ubstituted phenylacetic acid proceeded with aT ON of 415, an efficiency that was further extended to agram-scale reaction. [39] Under the standard conditions,t his reaction proceeds with 1mol %o fP d(OAc) 2 and in ag ram-scale experiment, aT ON of 186 was observed with 0.5 mol %ofthe catalyst. Theformation of less active palladium species by coordination with carboxylates derived from the substrate or product is therefore suppressed by the introduction of suitable ligands.…”

“…Pd-catalyzedC DC of o-xylene. [39] Angewandte Chemie aromatic substitution by an alkyne that is activated by Lewisacidic palladium species. Murrayastine synthesis by Pd-catalyzed oxidative cyclization.…”

Palladium(II)‐Catalyzed Tandem Synthesis of Acenes Using Carboxylic Acids as Traceless Directing Groups

“…[16] Our initial attempts with KHCO 3 were discour- [17] was also observed. Catalytic efficacy was considerably improved using Cs 2 CO 3 as the base; anthracene 3 a was obtained in 44 % yield, thus indicating that an overall tandem process was operating effectively.…”

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

“…[95] Als Alternative zu Allylhalogeniden zeigte die Gruppe von Gooßen, dass Allylacetate füre ine carboxylatdirigierte ortho-Allylierung von Benzoesäuren unter Rutheniumkatalyse verwendet werden kçnnen, und zwar nach einer Vorschrift, die mit sowohl elektronenreichen als auch elektronenarmen Substraten ebenso wie linearen als auch verzweigten Allylacetaten kompatibel war. [95] Als Alternative zu Allylhalogeniden zeigte die Gruppe von Gooßen, dass Allylacetate füre ine carboxylatdirigierte ortho-Allylierung von Benzoesäuren unter Rutheniumkatalyse verwendet werden kçnnen, und zwar nach einer Vorschrift, die mit sowohl elektronenreichen als auch elektronenarmen Substraten ebenso wie linearen als auch verzweigten Allylacetaten kompatibel war.…”