Mn(Ⅱ)-Catalyzed Cascade Annulations Of Alkyne-tethered N-Alkoxyamides

Isoquinolin-1(2H)-one is one of the most common structural units in natural products and bioactive compounds,and has important research value in the development of drugs and disease diagnosis.On the other hand,isoxazolidine,1,2-oxazinane and their derivatives skeletons are widely found in many drugs and natural products,as well as intermediates in various synthetic reactions.One of the effective strategies for designing drug molecules is to construct specific skeletons through multicyclization reactions.In this thesis,a series of isooxazolidine/1,2-oxazolidine fused isoquinolones were synthesized by C-H/N-H bond activation cyclization catalyzed by cheap manganese salt.The system does not need any additional oxidant.The reaction conditions are simple and the substrates have good generality.The multicyclization reaction can be realized simply and efficiently by one-pot methodN-((4-phenylbut-3-yn-1-yl)oxy)benzamide was used as a model substrate.After optimizing the reaction conditions,the final optimization conditions were determined: utilizing 5 mol % Mn(acac)2 as catalyst,the reaction was stirred at 80 ℃ for 12 h in MeCN(1.0 m L).The universality of N-alkoxyamide substrates was studied.The target products were obtained in moderate to good yield(up to 96%),and the possible reaction mechanism was preliminarily proposed.