A series of novel chiral phosphoramidite ligands based on chiral-bridged biphenyl backbones have been prepared conveniently and characterized. The ligands complexed with [IrCodCl]2 provided the first iridium catalyst system for the asymmetric addition of arylboronic acids to N-protected isatins with high efficiency. When performed in THF/H2O at 80 °C with 2 equiv of the arylboronic acids, the transformations acquired good to excellent results (up to 98% yield and 95% ee).
Highly enantioselective catalytic asymmetric intramolecular cascade imidization−nucleophilic addition− lactamization of N 1 -alkylethane-1,2-diamine with methyl 2-formylbenzoate catalyzed by a chiral phosphoric acid represents the first efficient method for the preparation of medicinally interesting chiral 2,3-dihydro-1H-imidazo[2,1-a]isoindol-5(9bH)-ones with high yields and excellent enantioselectivities. This strategy has been shown to be quite general toward various methyl 2-formylbenzoates.
A novel six-step synthesis of 7,8-difluoro-6,11-dihydrodibenzo[b,e]thiepin-11-ol (1) is described.
Starting with 3,4-difloro-2-methylbenzoic acid and using diphenyl
disulfide as an ideal sulfur source effectively solve the problems
such as harsh reaction conditions, usage of smelly thiophenol, which
might restrict the known process from pilot plant application. Large-scale
applicability of this new route has been successfully demonstrated
on kilogram-scale production to afford 1 with 98.04%
purity in 75% overall yield. Meanwhile, the corresponding impurity
profile was thus studied in detail and well documented.
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