Research On 1,3-dipolar Cycloaddition Reaction Based On ?-haloamide

A new method has been established which 1,2,4-oxadiazine-5-one derivatives and thiazolidine-4-one derivatives Synthesized by 1,3 dipolar cycloaddition reaction base on ?-bromoamide in an basic environment.In the first part of this paper,A new method has been established for the efficient synthesis of 1,2,4-oxadiazine-5-one derivatives with ?-bromoamide and Chlorimoxime in hexafluoro-2-propanol(HFIP)by 1,3-dipolar cycloaddition reaction in an alkaline environment.First,The reaction conditions was Optimized,and then,The development of the reaction substrates was investigated.reaction was investigated under the optimal reaction conditions.17 1,2,4-oxadiazine-5-one derivatives was obtained with a yield of up to 89%.The reaction mechanism for the reaction is based above condditions.Under the action of a base,the aza-oxyallylic cations are formed in situ when the ?-bromoamide removes one molecule of HBr and the nitrile oxides are formed in situ when the ruthenium chlorides were removed by the action of a base.The [3+3] cycloaddition reaction occurs between the aza-oxyallylic cations and the nitrile oxides,and the 1,2,4-oxadiazine-5-one derivatives were efficiently produced.The Excellent regioselectivity is due to the electronic and spatial effects of the two substrates.This reaction features simple-operation,mild conditions,and high regioselectivity.In the second part,A new method for synthesizing thiazolidine-4-one derivatives has been developed by cycloaddition reaction of ?-haloamide with isothiocyanate under the action of Na2CO3.First,the optimal conditions for the reaction were screened,next,we evaluated the generality of substrate.First,in terms of reaction mechanism,the [3+2] cycloaddition products are formed by reacting isothiocyanates with aza-oxyallylic cations,aza-oxyallylic cations are produced from the ?-bromoamide under the action of a base.The excellent regioselectivity is due to the electronic and spatial effects of the two substrates.This reaction features simple-operation,mild conditions,and high regioselectivity.22 thiazolidin-4-one derivatives were synthesized(up to a yield of 93%).