A series of optically active β-hydroxy sulfonamides were synthesized for the first time by asymmetric transfer hydrogenation of the corresponding β-ketosulfonamides using the Ru–TsDPEN–HCOOH–Et3N catalytic system, in excellent yields (up to 95%) with excellent diastereo- (up to > 99:1 dr) and enantioselectivities (up to >99% ee).
The Gabriel synthesis is generalized as monoalkylation of an ammonia or primary amine derivative with subsequent removal of the derivatizing group(s) from nitrogen. Two new derivatives for this purpose are introduced: phenacylsulfonamides and triflamides, with discussion of their generality and effectiveness.
Asymmetric Hydrogenation of β-Keto Sulfonamides and β-Keto Sulfones with a Chiral Cationic Ruthenium Diamine Catalyst
作者:Xiao-Fei Huang、Shao-Yun Zhang、Zhi-Cong Geng、Chun-Yuen Kwok、Peng Liu、Hai-Yan Li、Xing-Wang Wang
DOI:10.1002/adsc.201300331
日期:2013.10.11
AbstractOptically active β‐hydroxy sulfonamides and β‐hydroxy sulfones are very important building blocks for the preparation of bioactive compounds and pharmaceuticals. In this work, a highly efficient asymmetric hydrogenation of β‐keto sulfonamides and β‐keto sulfones has been developed using the phosphine‐free chiral ruthenium complex Ru(OTf)(TsDPEN)(η6‐p‐cymene) as the catalyst, to afford the corresponding β‐hydroxy sulfonamides and β‐hydroxy sulfones in high yields with excellent optical purities. In addition, a cascade asymmetric hydrogenation/dynamic kinetic resolution (DKR) of racemic cyclic β‐keto sulfonamides and β‐keto sulfones was also realized using the same catalyst, to give the corresponding chiral cyclic β‐hydroxy sulfonamides and β‐hydroxy sulfones in good yields with excellent enantio‐ and diastereoselectivities.magnified image