Directed Palladium-Catalyzed Acetoxylation of Indolines. Total Synthesis of N-Benzoylcylindrocarine

Abstract

We describe a palladium catalyzed C7-acetoxylation of indolines with a range of amide directing groups. While a variety of substituents are tolerated on the indoline-core and the N1-acyl group, the acetoxylation is most sensitive to the C2-and C6-indoline substituents. The practicality of this indoline C7-acetoxylation is demonstrated using a cinnamamide substrate on mmol-scale. Several N1-acyl groups, including those present in natural alkaloids, guide C7-acetoxylation of indoline substrates over a competitive C5-oxidation. The application of this chemistry allowed for the first synthesis of N-benzoylcylindrocarine by late-stage C17-acetoxylation of Nbenzoylfendleridine.

Ru(II)-Catalyzed Synthesis of Fused Imidazo[1,2-a]pyridine-chromenones and Methylene-Tethered Bis-imidazo[1,2-a]pyridines and Regioselective O-Acetoxylation of Imidazo[1,2-a]pyridines

“…18 Recently, Movassaghi and co-workers have reported a Pd(II)-catalyzed regioselective acetoxylation of indolines in the presence of PIDA as an oxidant in acetic acid using amide as a directing group. 19 After being inspired by these findings and to establish the versatility of this chemistry, we successfully optimized the reaction conditions for the Ru-catalyzed regioselective C-(sp 2 )−H mono-and diacetoxylation of imidazo[1,2-a]pyridine with PhI(OAc) 2 , and next, we tried to broaden the substrate scope. Apart from simple IP 4a, methyl-and bromo-substituted substrates were also used in this reaction and gave the desired products 4b and 4c, respectively, in moderate yields of 42− 51%.…”

“…This protocol provides a variety of acetoxylated products that are potentially of great importance in medicinal chemistry, and these bonds are common structural units in pharmaceuticals, agrochemicals, and polymers . Recently, Movassaghi and co-workers have reported a Pd­(II)-catalyzed regioselective acetoxylation of indolines in the presence of PIDA as an oxidant in acetic acid using amide as a directing group . After being inspired by these findings and to establish the versatility of this chemistry, we successfully optimized the reaction conditions for the Ru-catalyzed regioselective C­(sp 2 )–H mono- and diacetoxylation of imidazo­[1,2- a ]­pyridine with PhI­(OAc) 2 , and next, we tried to broaden the substrate scope.…”

RhRu Bimetallic Oxide Cluster Catalysts for Cross-Dehydrogenative Coupling of Arenes and Carboxylic Acids

“…Cross-dehydrogenative coupling (CDC) reactions between aromatic C–H and X–H (X = C, N, O) bonds have recently attracted considerable interest owing to their step/atom economy. − CDC reactions between arenes and carboxylic acids can produce aryl esters directly from nonactivated substrates . Homogeneous catalysts such as Co, Ru, − Rh, − Pd, − and Au , complexes have been developed for the coupling of arenes and carboxylic acids (Figure a). Oxidants are generally required for these reactions to occur.…”