Using Nazarov Electrocyclization to Stage Chemoselective [1,2]-Migrations: Stereoselective Synthesis of Functionalized Cyclopentenones
作者:David Lebœuf、Jie Huang、Vincent Gandon、Alison J. Frontier
DOI:10.1002/anie.201104870
日期:2011.11.11
Highly functionalizedcyclopentenones have been prepared stereospecifically through a chemoselective copper(II)‐mediated Nazarov/Wagner–Meerwein rearrangement sequence. After the initial 4π electrocyclization, this reaction involves two sequential [1,2]‐migrations depending upon both migratory ability and steric bulk of the substituents at C1 and C5 (see scheme). The proposed mechanism of the reaction
A highly efficient asymmetric hydrogenation of α-substituted α,β-unsaturated acyclic ketones catalyzed by chiral spiro iridium complexes for the preparation of chiral 2-substituted allylicalcohols has been developed (ee up to 99.7%). This method provides a concise route to (−)-mesembrine (34% yield, 12 steps).
Unlocking the Asymmetric Hydrogenation of Tetrasubstituted Acyclic Enones
作者:Jorge Faiges、Maria Biosca、Miquel A. Pericàs、Maria Besora、Oscar Pàmies、Montserrat Diéguez
DOI:10.1002/anie.202315872
日期:2024.2.26
Fast and highly selective Ir-catalysts have been developed for the asymmetric hydrogenation of challenging tetrasubstituted acyclicenones. The mechanism and the effects of the catalyst and reaction parameters on selectivity have been unraveled by means of deuterogenation experiments and DFT calculations.