作者:Jørn E. Tungen、Jens M. J. Nolsøe、Trond V. Hansen
DOI:10.1021/ol302798g
日期:2012.12.7
Asymmetric iodolactonization of gamma- and delta-unsaturated carboxylic acids has been explored in the presence of six different chiral organocatalysts 5-8. The catalyst 6b was found to facilitate the cyclization of 5-arylhex-5-enoic acids 1 to the corresponding iodolactones 2 with up to 96% ee. By this protocol, unsaturated carboxylic acids are converted enantioselectively to synthetically useful delta-lactones in high yields using commercially available NIS. Apparently, both hydrogen bonding and aryl/aryl interactions are important for efficient stereodifferentiation.
The Role of Ni-Carboxylate During Catalytic Asymmetric Iodolactonization Using PyBidine-Ni(OAc)2
作者:Takayoshi Arai、Satoshi Kajikawa、Eri Matsumura
DOI:10.1055/s-0033-1339676
日期:——
The combination of a PyBidine-Ni(OAc)(2) complex with a catalytic amount of iodine efficiently catalyzed asymmetric iodolactonization to generate chiral iodolactones with up to 89% enantiomeric excess. The formation of an intermediate Ni-carboxylate species from the alkenyl carboxylic acid is a key role in promoting the iodolactonization.