摘要
Herein,we report a condition-controlled divergent synthesis of spiro indene-2,1'-isoindolinones and spiro isochroman-3,1'-isoindolinones through cobalt-catalyzed formal[4+1]and[4+1+1]spirocyclization of aromatic amides with 2-diazo-1H-indene-1,3(2H)-dione.When the reaction is carried out under air in ethyl acetate,spiro indene-2,1'-isoindolinones are formed through Co(II)-catalyzed C—H/N—H[4+1]spirocyclization.When the reaction is run under O2 in CH3CN,on the other hand,spiro isochroman-3,1'-isoindolinones are generated through Baeyer-Villiger oxidation of the in situ formed spiro indene-2,1'-isoindolinones with O2 as a cheaper and environmental-friendly oxygen source.In general,these protocols have advantages such as using non-precious and earth-abundant metal catalyst,no extra additive,high efficiency and regioselectivity.A gram-scale synthesis and the removal of the directing group further highlight its utility.
基金
the National Natural Science Foundation of China(22101075,U2004189)
Central Plains Science and Technology Innovation Leader Project(224200510009)
Postdoctoral Research Grant in Henan Province(202103085)
Henan Key Laboratory of Organic Functional Molecules and Drug Innovation,and 111 Project(D17007)for financial support.
