Palladium-catalyzed carbonylative domino synthesis

A facile and selective palladium-catalyzed carbonylative domino synthesis of benzothiophenes was developed by Alper and Zeng in 2011 [273]. 2-Carbon-ylbenzo[Z ] thiophene derivatives were produced from 2-gem-dihalovinylthiophe-nols in 24-73 % yields (Scheme 2.39). This protocol involved an intramolecular C-S coupling/intermolecular carbonylation cascade sequence and allowed for access to various highly functionalized benzo[h]thiophenes. 

A 2009 paper described a palladium-catalyzed domino-C,N-coupling/carbonyl-ation/Suzuki coupling reaction was used provide an efficient synthesis of 2-aroyl-/ heteroaroylindoles [163]. For instance, 2-ge/M-dibromovinyIaniline 118 and 3-furyl-boronic acid under carbon monoxide afforded 3-fuiylindole 119 in 67% yield. 

The palladium(II)-catalyzed olefin carbonylation reaction was first reported more than 30 years ago in studies by Stille and co-workers and James et al. The reaction of carbon monoxide with cis- and tra 5-but-2-ene in methanol in the presence of palladium(II)-chloride and copper(II)-chloride yielded threo- and eryt/zro-3-methoxy-2-methyl-butanoate, respectively. The transformation that was based on the well-known Wacker process for oxidation of ethylene into acetaldehyde in water " is now broadly defined as the Pd(II)-catalyzed oxycarbonylation of the unsaturated carbon-carbon bonds. This domino reaction includes oxypalladation of alkenes, migratory insertion of carbon monoxide, and alkoxylation. Since the development of this process, several transformations mediated by palladium(II) compounds have been described. The direct oxidative bisfunctionalization of alkenes represents a powerful transformation in the field of chemical synthesis. Palladium(II)-promoted carbonylation of alkenes in the presence of water/alcohol may lead to alkyl carboxylic acids (hydrocarboxylation), diesters [bis(aIkoxycarbonyla-tion)], (3-alkoxy carboxylic acids (alkoxy-carboxylation), or (3-alkoxy esters (alkoxy-carbonylation or alkoxy-alkoxy-carbonylation). Particularly attractive features of these multitransformation processes include the following ... 

---