A versatile method for the synthesis of 3,3-diaryloxindoies via Pd-catalyzed alpha-arylations or an SNAr reaction is described. The reaction proceeds using mild base, is tolerant of a variety of functional groups, and is capable of preparing hindered all-carbon quaternary centers.
The Palladium Catalyzed Asymmetric Addition of Oxindoles and Allenes: An Atom-Economical Versatile Method for the Construction of Chiral Indole Alkaloids
作者:Barry M. Trost、Jia Xie、Joshua D. Sieber
DOI:10.1021/ja209244m
日期:2011.12.21
The Pd-catalyzed asymmetricallylicalkylation (AAA) is one of the most useful and versatile methods for asymmetric synthesis known in organometallic chemistry. Development of this reaction over the past 30 years has typically relied on the use of an allylic electrophile bearing an appropriate leaving group to access the reactive Pd(π-allyl) intermediate that goes on to the desired coupling product
A catalyst generated from Pd(dba)(2) and the bulky electron-rich phosphine ligand 2-(dicyclohexylphosphino)-2',4', 6'-tri-i-propyl-1 - 1'-biphenyl is effective for the alpha-arylation of oxindoles. Generation of the potassium-enolates of a range of oxindoles allows coupling with aryl chlorides, bromides, and triflates. Significant variation of the substitution pattern on both the oxindole and aryl halide is possible.