1-Oxa-2-azaspiro[2.5]octane,as one of N-H oxaziridines,is a selective electrophilic aminating agent for N-,S-,C-,and O-nucleophiles.It has the features of stereoselectivity and the absence of formation of strongly aci...1-Oxa-2-azaspiro[2.5]octane,as one of N-H oxaziridines,is a selective electrophilic aminating agent for N-,S-,C-,and O-nucleophiles.It has the features of stereoselectivity and the absence of formation of strongly acidic or basic byproducts,leading to considerable interest in the development of organic synthetic methods.Currently,the economically feasible route of production of 1-oxa-2-azaspiro[2.5]octane is the reaction of cyclohexanone with ammonia and sodium hypochlorite.However,due to strong exothermic reactions,massive gas release and heterogeneous reaction,the controllability,efficiency and safety of the reaction are in great difficulty using batch technology.In this paper,a microreaction system containing predispersion,reaction and phase separation was introduced into the preparation of 1-oxa-2-azaspiro[2.5]octane.The research results showed that precise control of the process including droplet dispersion,temperature control,reaction time control and fast continuous phase separation,was the key to process intensification.Under optimal conditions,the concentration of 1-oxa-2-azaspiro[2.5]octane in product obtained by microreaciton system(~2.0 mol·L^(-1))was much higher than that obtained by batch technology(0.2-0.4 mol·L^(-1)),which demonstrated that the continuous-flow synthesis would be a more efficient substitute for batch synthesis.Meanwhile,the results of the derivation experiments also showed that the aminating agent solution with higher concentration was more advantageous in the applications.展开更多
A simple one-pot procedure for the preparation of imines from the corresponding aldehydes and amines, and their subsequent oxidation reaction with m-CPBA to produce synthetically useful oxaziridines is reported. The m...A simple one-pot procedure for the preparation of imines from the corresponding aldehydes and amines, and their subsequent oxidation reaction with m-CPBA to produce synthetically useful oxaziridines is reported. The method is applicable to imines derived from both aliphatic and aromatic aldehydes and diverse alkyl amines. Short reaction times, essentially quantitative yields, very mild reaction conditions, and easy purification are the main features of the procedure reported herein.展开更多
Chirality transformation is a basic,attractive,and important strategy for obtaining enantioenriched products with desired chiral elements.The reported chirality conversion reaction often involves the process from one ...Chirality transformation is a basic,attractive,and important strategy for obtaining enantioenriched products with desired chiral elements.The reported chirality conversion reaction often involves the process from one type of chirality to another one.To better utilize the chirality transformation strategy for obtaining two or more products with different chiral elements in a single reaction,a new method of kinetic resolution accompanied by a chirality transformation protocol is proposed and successfully realized in this study.This process is used for the asymmetric oxidation of phenol compounds along with the kinetic resolution of oxaziridines.A wide scope of products,including axially chiral phenols,oxaziridines,andα-hydroxyl cyclic ketones were smoothly obtained in high levels of yields and enantioselectivities in the developed method.These products can be readily used for the synthesis of various types of chiral ligands,which are potential choices for other catalytic asymmetric reactions.展开更多
基金the support of the National Natural Science Foundation of China(22108264)for this work。
文摘1-Oxa-2-azaspiro[2.5]octane,as one of N-H oxaziridines,is a selective electrophilic aminating agent for N-,S-,C-,and O-nucleophiles.It has the features of stereoselectivity and the absence of formation of strongly acidic or basic byproducts,leading to considerable interest in the development of organic synthetic methods.Currently,the economically feasible route of production of 1-oxa-2-azaspiro[2.5]octane is the reaction of cyclohexanone with ammonia and sodium hypochlorite.However,due to strong exothermic reactions,massive gas release and heterogeneous reaction,the controllability,efficiency and safety of the reaction are in great difficulty using batch technology.In this paper,a microreaction system containing predispersion,reaction and phase separation was introduced into the preparation of 1-oxa-2-azaspiro[2.5]octane.The research results showed that precise control of the process including droplet dispersion,temperature control,reaction time control and fast continuous phase separation,was the key to process intensification.Under optimal conditions,the concentration of 1-oxa-2-azaspiro[2.5]octane in product obtained by microreaciton system(~2.0 mol·L^(-1))was much higher than that obtained by batch technology(0.2-0.4 mol·L^(-1)),which demonstrated that the continuous-flow synthesis would be a more efficient substitute for batch synthesis.Meanwhile,the results of the derivation experiments also showed that the aminating agent solution with higher concentration was more advantageous in the applications.
文摘A simple one-pot procedure for the preparation of imines from the corresponding aldehydes and amines, and their subsequent oxidation reaction with m-CPBA to produce synthetically useful oxaziridines is reported. The method is applicable to imines derived from both aliphatic and aromatic aldehydes and diverse alkyl amines. Short reaction times, essentially quantitative yields, very mild reaction conditions, and easy purification are the main features of the procedure reported herein.
基金supported by the Innovation Fund for Medical Sciences(CIFMS,2019-I2M-5-074,2021-I2M-1-026,2021-I2M-3-001)the Fundamental Research Funds for the Central Universities(lzujbky-2022-ey11,lzujbky-2022-40)the Funds for Fundamental Research Creative Groups of Gansu Province(20JR5RA310)。
文摘Chirality transformation is a basic,attractive,and important strategy for obtaining enantioenriched products with desired chiral elements.The reported chirality conversion reaction often involves the process from one type of chirality to another one.To better utilize the chirality transformation strategy for obtaining two or more products with different chiral elements in a single reaction,a new method of kinetic resolution accompanied by a chirality transformation protocol is proposed and successfully realized in this study.This process is used for the asymmetric oxidation of phenol compounds along with the kinetic resolution of oxaziridines.A wide scope of products,including axially chiral phenols,oxaziridines,andα-hydroxyl cyclic ketones were smoothly obtained in high levels of yields and enantioselectivities in the developed method.These products can be readily used for the synthesis of various types of chiral ligands,which are potential choices for other catalytic asymmetric reactions.
