Department of Chemistry, University of Pennsylvania, 231 S 34th St, Philadelphia, PA 19104, United States.
Chem Asian J. 2020 Apr 1;15(7):1039-1043. doi: 10.1002/asia.201901727. Epub 2020 Mar 11.
An oxidative catalytic vanadium(V) system was developed to access the naturally nonabundant diastereomers of carpanone from the corresponding alkenyl phenol monomer in one pot by tandem oxidation, oxidative coupling, and 4+2 cyclization. This system was applied to the synthesis of two other analogues of carpanone. Mild oxidizing silver salts were used as the terminal oxidant to minimize background oxidation which produces the natural diastereomer of carpanone. Further, the first examples of enantioselective oxidative benzoxanthenone formation are reported. Solvent polarity has a strong effect on enantioselectivity, consistent with a mechanism involving binding of vanadium Schiff base catalysts to the alcoholic moiety of the alkenyl phenols during the cyclization step.
开发了一种氧化催化的钒(V)体系，可通过串联氧化、氧化偶联和 4+2 环化，从相应的烯基苯酚单体一锅法获得天然非丰富的卡潘酮非对映异构体。该体系被应用于另外两种卡潘酮类似物的合成。温和的氧化银盐被用作末端氧化剂，以最大限度地减少产生卡潘酮天然非对映异构体的背景氧化。此外，还报道了首例对映选择性氧化苯并氧杂蒽酮形成的例子。溶剂极性对对映选择性有很强的影响，这与一种机制一致，即在环化步骤中，钒希夫碱催化剂与烯基苯酚的醇部分结合。
