Secondary amides are a class of highly stable compounds serving as versatile starting materials,intermediates and directing groups（amido groups） in organic synthesis.The direct deacylation of secondary amides to rel...Secondary amides are a class of highly stable compounds serving as versatile starting materials,intermediates and directing groups（amido groups） in organic synthesis.The direct deacylation of secondary amides to release amines is an important transformation in organic synthesis.Here,we report a protocol for the deacylation of secondary amides and isolation of amines.The method is based on the activation of amides with Tf_2O.followed by addition of organocerium reagents,and acidic work-up.The reaction proceeded under mild conditions and afforded the corresponding amines,isolated as their hydrochloride salts,in good yields.In combination with the C-H activation functionalization methodology,the method is applicable to the functionalization of aniline as well as conversion of carboxylic derivatives to functionalized ketones.展开更多
The direct partial reduction of highly stable secondary amides to more reactive aldimines and aldehydes is a challenging yet highly demanding transformation. In this context, only three methods have been reported. We ...The direct partial reduction of highly stable secondary amides to more reactive aldimines and aldehydes is a challenging yet highly demanding transformation. In this context, only three methods have been reported. We report herein an improved version of the Charette's method. Our protocol consists of activation of secondary amides with triflic anhydride/2-fluoropyridine,and partial reduction of the resulting intermediates with 1,1,3,3-tetramethyldisiloxane(TMDS), which delivered aldimines or aldehydes upon acidic hydrolysis. Aromatic amides were reduced to the corresponding aldimines in 85%–100% NMR yields,and yields(NMR) from aliphatic amides were 72%–86%. Acidic hydrolysis of the aldimine intermediates afforded, in one-pot,the corresponding aldehydes in 80%–96% yields. A simple protocol was established to isolate labile aldimines in pure form in92%–96% yields. The improved method gave generally higher yields as compared to the known ones, and features the use of cheaper and more atom-economical TMDS as a chemoselective reducing agent. In addition, a convenient extraction protocol has been established to allow the isolation of amines, which constitutes a mild method for the N-deacylation of amides, another highly desirable transformation. The extended method retains the advantages of the original method of Charette in terms of mild conditions, good functional group tolerance, and excellent chemoselectivity.展开更多
基金financial support from the National Natural Science Foundation of China(No.21332007)the Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT) of Ministry of Education+1 种基金the Fundamental Research Funds for the Central Universities(No.20720150044)the Natural Science Foundation of Fujian Province of China (No.2014J01062)
文摘Secondary amides are a class of highly stable compounds serving as versatile starting materials,intermediates and directing groups（amido groups） in organic synthesis.The direct deacylation of secondary amides to release amines is an important transformation in organic synthesis.Here,we report a protocol for the deacylation of secondary amides and isolation of amines.The method is based on the activation of amides with Tf_2O.followed by addition of organocerium reagents,and acidic work-up.The reaction proceeded under mild conditions and afforded the corresponding amines,isolated as their hydrochloride salts,in good yields.In combination with the C-H activation functionalization methodology,the method is applicable to the functionalization of aniline as well as conversion of carboxylic derivatives to functionalized ketones.
基金supported by the National Natural Science Foundation of China(21332007)Xiamen University
文摘The direct partial reduction of highly stable secondary amides to more reactive aldimines and aldehydes is a challenging yet highly demanding transformation. In this context, only three methods have been reported. We report herein an improved version of the Charette's method. Our protocol consists of activation of secondary amides with triflic anhydride/2-fluoropyridine,and partial reduction of the resulting intermediates with 1,1,3,3-tetramethyldisiloxane(TMDS), which delivered aldimines or aldehydes upon acidic hydrolysis. Aromatic amides were reduced to the corresponding aldimines in 85%–100% NMR yields,and yields(NMR) from aliphatic amides were 72%–86%. Acidic hydrolysis of the aldimine intermediates afforded, in one-pot,the corresponding aldehydes in 80%–96% yields. A simple protocol was established to isolate labile aldimines in pure form in92%–96% yields. The improved method gave generally higher yields as compared to the known ones, and features the use of cheaper and more atom-economical TMDS as a chemoselective reducing agent. In addition, a convenient extraction protocol has been established to allow the isolation of amines, which constitutes a mild method for the N-deacylation of amides, another highly desirable transformation. The extended method retains the advantages of the original method of Charette in terms of mild conditions, good functional group tolerance, and excellent chemoselectivity.
