Regioselective Cycloaddition of 3-Azetidinones and 3-Oxetanones with Alkynes through Nickel-Catalysed Carbon-Carbon Bond Activation
作者:Kelvin Y. T. Ho、Christophe Aïssa
DOI:10.1002/chem.201200167
日期:2012.3.19
Get in the ring! The first examples of transition‐metal‐catalysed CC bond activation of 3‐azetidinones and 3‐oxetanones are reported. In the presence of a nickel catalyst and alkynes, a regioselective and high‐yielding [4+2] cycloaddition occurs, leading to the formation of pyridinones, pyranones and eventually 4,5‐disubstituted 3‐hydroxypyridines (see scheme).
An <i>in Situ</i> Approach to Nickel-Catalyzed Cycloaddition of Alkynes and 3-Azetidinones
作者:Ashish Thakur、Judah L. Evangelista、Puneet Kumar、Janis Louie
DOI:10.1021/acs.joc.5b01458
日期:2015.10.16
An efficient and convenient procedure that generates the active Ni(0) catalyst in situ from cheap, air stable Ni(II) precursors is developed for the [4 + 2]-cycloaddition of alkynes and 3-azetidinones. The reaction affords useful 3-dehydropiperidinones in comparable yields to the reported Ni(0) procedure. Additionally, the cycloaddition with 3-oxetanone afforded the 3-dehydropyranone product. Chiral 2-substituted azetidinones were also tolerated to form substituted dehydropiperidinones in high yield and enantiomeric excess.