Rhodium(<scp>iii</scp>)-catalyzed asymmetric [4+1] spiroannulations of <i>O</i>-pivaloyl oximes with α-diazo compounds
作者:Lincong Sun、Bingxian Liu、Yanlian Zhao、Junbiao Chang、Lingheng Kong、Fen Wang、Wei-Qiao Deng、Xingwei Li
DOI:10.1039/d1cc02888j
日期:——
Chiral RhIII catalysts can catalyze the asymmetric [4+1] spiroannulation of O-pivaloyl oximes with α-diazo homophthalimides under redox-neutral and acid/base-neutral conditions, leading to formation of chiral spirocyclic imines as a result of C–H activation and N–O cleavage. The reaction proceeded with high efficiency and features broad substrate scope, mild reaction conditions, and high to excellent
dihydrobenzofuran-fused pyridones in moderate to good yields with good functional group compatibility. The reaction likely involves a radical relay annulation, leading to the ring opening of the lactone moiety of the coumarins, and simultaneous formation of three new bonds. The investigation of photoluminescent properties reveals that several obtained compounds may have potential as fluorescent materials.
A useful Cu-catalyzed cycloaddition protocol for the construction of benzene rings has been achieved. The reactions, utilizing readily available oximes and maleimides as starting materials, proceed under mild reaction conditions to generate a series of structurally interesting fused-phthalimides that are difficult to be prepared by conventional methods.
transformation of an oxindole core into a quinolinone skeleton, which generates several structurally new pyridine-fused quinolinones. The synergistic reactions allow expansion of a five-membered lactam ring by radical cation-triggered C–C bondcleavage and enable a further intramolecular cyclization with the aim to construct totally distinct core skeletons.