Stereochemical control–-nitrones from oximes by 1,3-azaprotio cyclotransfer or 1,2-prototropy
作者:Colm O'Mahony、Frances Heaney
DOI:10.1039/cc9960000167
日期:——
Oximes 1a,b and 10 are configurationally stable at elevated temperatures, the (E)-oximes react exclusively via a concerted 1,3-azaprotio cyclotransfer reaction to give 6- and 7-membered cyclic dipoles, respectively, whilst their Z-isomers react via a 1,2-prototropy-cycloaddition sequence furnishing fused isoxazolidines.
Nitrone and Alkyne Cascade Reactions for Regio‐ and Diastereoselective 1‐Pyrroline Synthesis
作者:Guanqun Zhang、Abdullah S. Alshreimi、Laura Alonso、Alan Antar、Hsien‐Cheng Yu、Shahidul M. Islam、Laura L. Anderson
DOI:10.1002/anie.202101511
日期:2021.6
The synthesis of 1-pyrrolines from N-alkenylnitrones and alkynes has been explored as a retrosynthetic alternative to traditional approaches. These cascade reactions are formal [4+1] cycloadditions that proceed through a proposed dipolar cycloaddition and N-alkenylisoxazoline [3,3′]-sigmatropic rearrangement. A variety of cyclic alkynes and terminal alkynes have been shown to undergo the transformation