Novel Methodology for the Efficient Synthesis of 3-Aryloxindoles: [1,2]-Phospha-Brook Rearrangement–Palladium-Catalyzed Cross-Coupling Sequence
作者:Masahiro Terada、Azusa Kondoh、Akira Takei
DOI:10.1055/s-0035-1561859
日期:——
A novelmethodology for the efficient synthesis of 3-aryloxindoles from isatin derivatives was developed. The methodology involves the formation of an oxindole having a phosphate moiety at the C-3 position via the [1,2]-phospha-Brook rearrangement under Bronsted base catalysis followed by palladium-catalyzed cross-coupling with aryl boron reagents. The one-pot synthesis of 3-aryloxindoles from isatin
Highly enantioselective phase-transfer alkylation of 3-substituted-2-oxindoles with activated bromomethanes is disclosed with a broad substrate scope by using bicyclic guanidinium as a catalyst and a Lewis acid as the co-catalyst. The alkylation adducts are versatile intermediates to accomplish the syntheses of pyrroloindolines and furoindolines.
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.