A facile, rapid and regioselective method for the 1-O-deacylation of peracylated glycopyranoses is described which occurs under mild conditions by absorption onto alumina using microwave irradiation.
Synthesis of the optically active metabolite of clausenamide CM2 (3, 5-dihydroxy- 5-(a-hydroxylbenzyl)-1-methyl-4-benzylpyrrolidin-2-one) from 3-O-acetyl- clausenamide was described.
The behavior of α,α-diacetyl ketene dibenzylthioacetal 1a under basic conditions was studied. Catalyzed by steric hindered base as t-BuONa(in t-BuOH), α-acetyl ketene dibenzylthioacetal 2a could be obtained in 98% ...The behavior of α,α-diacetyl ketene dibenzylthioacetal 1a under basic conditions was studied. Catalyzed by steric hindered base as t-BuONa(in t-BuOH), α-acetyl ketene dibenzylthioacetal 2a could be obtained in 98% yield within 3 min via deacylation of 1a. Assisted by t-BuONa(in t-BuOH), α-cinnamoyl ketene dibenzylthioacetals were produced in high yields by reacting both 1a and 2a with arylaldehydes; whereas, under the same conditions, the corresponding α,α-dicinnamoyl ketene dibenzylthioacetals 4 were formed when furan-2-carbaldehyde and thiophene-2-carbaldehyde were used as the electrophiles. These evidences support the proposed mechanism that, catalyzed by t-BuONa (in t-BuOH), the reaction of 1a with arylaldehydes may normally proceed via a sequential deacylation-condensation process and the formation of double condensation products 4 may be due to the higher activity of furan-2-carbaldehyde and thiophene-2-carbaldehyde under the selected reaction conditions.展开更多
N-acetyl-D-methionine, NaAc and the remains of N-acetyl-L-methionine dramatically affect the purification of L-methionine when purified from the mixture of enzymatically deacylated N-acetyl-DL-methionine, leading to a...N-acetyl-D-methionine, NaAc and the remains of N-acetyl-L-methionine dramatically affect the purification of L-methionine when purified from the mixture of enzymatically deacylated N-acetyl-DL-methionine, leading to a low yield conventionally. Here, this paper reports a successful separation and purification of both L-methionine and N-acetyl-D-methionine by an H ion-exchange column. The pH, L-Met concentration and the ratio between the content of sodium cation and the ion-exchange capacity were optimized to obtain the maximum yield. Experimental results indicate that, under the optimized conditions, the yields of L-methionine and N-acetyl-D-methionine can reach as high as 85% and 75%, respectively.展开更多
The deacylation of amides,which is widely employed in the pharmaceutical industry,is not a fast reaction under normal conditions.To intensify this reaction,a high-temperature and high-pressure continuous microreaction...The deacylation of amides,which is widely employed in the pharmaceutical industry,is not a fast reaction under normal conditions.To intensify this reaction,a high-temperature and high-pressure continuous microreaction technology was developed,whose space-time yield was 49.4 times that of traditional batch reactions.Using the deacylation of acetanilide as a model reaction,the effects of the temperature,pressure,reaction time,molar ratio of reactants,and water composition on acetanilide conversion were carefully studied.Based on the rapid heating and cooling capabilities,the kinetics of acetanilide deacylation at high temperatures were investigated to determine the orders of reactants and activation energy.This microreaction technology was further applied to a variety of other amides to understand the influence of substituents and steric hindrance on the deacylation reaction.展开更多
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
Sirtuins(SIRTs)are nicotinamide adenine dinucleotide(NAD^+)-dependent histone deacetylases with diverse physiological functions.A variety of small molecules have been developed to interrogate the physiological functio...Sirtuins(SIRTs)are nicotinamide adenine dinucleotide(NAD^+)-dependent histone deacetylases with diverse physiological functions.A variety of small molecules have been developed to interrogate the physiological function of SIRTs.Therefore,it is desirable to establish efficient and convenient assays to screen SIRTs modulators.In this study,we designed a series of fluorescent nonapeptide probes derived from substrates of SIRTI-SIRT3.Fluorescence increment of these probes is based on SIRT-mediated removal of the acyl side chain with fluorophore,which makes this system free of lysine-recognizing protease.Comparing the reaction of these fluorescent nonapeptide substrates with SIRT1-SIRT3 and SIRT6,it was confirmed that this assessment system was the most suitable for SIRT2activity detection.Thus,SIRT2 was used to modify substrates by truncating the amino acids or lysine side chain of nonapeptide.Finally,two specific and efficient fluorescent probes for SIRT2,ne-D9 and ne-K4a,were developed.Evaluation of the results revealed that ne-K4a based assay was more suitable for modulators screening in vitro,while the other specific substrate ne-D9 was stable in cell lysate and could detect the activity of SIRT2 in the same.In summary,this study presents a novel strategy for detecting SIRT2 activity in vitro and in cell lysate.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This work was financially supported by the National Natural Science Foundation of China(No.20272051).
文摘A facile, rapid and regioselective method for the 1-O-deacylation of peracylated glycopyranoses is described which occurs under mild conditions by absorption onto alumina using microwave irradiation.
基金This work was supported by the National Natural Science Foundation of China. ( No.29790121)
文摘Synthesis of the optically active metabolite of clausenamide CM2 (3, 5-dihydroxy- 5-(a-hydroxylbenzyl)-1-methyl-4-benzylpyrrolidin-2-one) from 3-O-acetyl- clausenamide was described.
文摘The behavior of α,α-diacetyl ketene dibenzylthioacetal 1a under basic conditions was studied. Catalyzed by steric hindered base as t-BuONa(in t-BuOH), α-acetyl ketene dibenzylthioacetal 2a could be obtained in 98% yield within 3 min via deacylation of 1a. Assisted by t-BuONa(in t-BuOH), α-cinnamoyl ketene dibenzylthioacetals were produced in high yields by reacting both 1a and 2a with arylaldehydes; whereas, under the same conditions, the corresponding α,α-dicinnamoyl ketene dibenzylthioacetals 4 were formed when furan-2-carbaldehyde and thiophene-2-carbaldehyde were used as the electrophiles. These evidences support the proposed mechanism that, catalyzed by t-BuONa (in t-BuOH), the reaction of 1a with arylaldehydes may normally proceed via a sequential deacylation-condensation process and the formation of double condensation products 4 may be due to the higher activity of furan-2-carbaldehyde and thiophene-2-carbaldehyde under the selected reaction conditions.
文摘N-acetyl-D-methionine, NaAc and the remains of N-acetyl-L-methionine dramatically affect the purification of L-methionine when purified from the mixture of enzymatically deacylated N-acetyl-DL-methionine, leading to a low yield conventionally. Here, this paper reports a successful separation and purification of both L-methionine and N-acetyl-D-methionine by an H ion-exchange column. The pH, L-Met concentration and the ratio between the content of sodium cation and the ion-exchange capacity were optimized to obtain the maximum yield. Experimental results indicate that, under the optimized conditions, the yields of L-methionine and N-acetyl-D-methionine can reach as high as 85% and 75%, respectively.
基金We gratefully acknowledge the financial support from the National Natural Science Foundation of China(Grant No.21991104)the Shandong Province Major Science and Technology Innovation Project(Grant No.2019JZZY020401).
文摘The deacylation of amides,which is widely employed in the pharmaceutical industry,is not a fast reaction under normal conditions.To intensify this reaction,a high-temperature and high-pressure continuous microreaction technology was developed,whose space-time yield was 49.4 times that of traditional batch reactions.Using the deacylation of acetanilide as a model reaction,the effects of the temperature,pressure,reaction time,molar ratio of reactants,and water composition on acetanilide conversion were carefully studied.Based on the rapid heating and cooling capabilities,the kinetics of acetanilide deacylation at high temperatures were investigated to determine the orders of reactants and activation energy.This microreaction technology was further applied to a variety of other amides to understand the influence of substituents and steric hindrance on the deacylation reaction.
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 in part by the National Natural Science Foundation of China(31671437)the Natural Science Foundation of Guangdong Province,China(2016A030313335)+1 种基金the Guangdong Provincial Key Laboratory of Construction Foundation,China(2017B030314030)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program,China(2017BT01Y093).
文摘Sirtuins(SIRTs)are nicotinamide adenine dinucleotide(NAD^+)-dependent histone deacetylases with diverse physiological functions.A variety of small molecules have been developed to interrogate the physiological function of SIRTs.Therefore,it is desirable to establish efficient and convenient assays to screen SIRTs modulators.In this study,we designed a series of fluorescent nonapeptide probes derived from substrates of SIRTI-SIRT3.Fluorescence increment of these probes is based on SIRT-mediated removal of the acyl side chain with fluorophore,which makes this system free of lysine-recognizing protease.Comparing the reaction of these fluorescent nonapeptide substrates with SIRT1-SIRT3 and SIRT6,it was confirmed that this assessment system was the most suitable for SIRT2activity detection.Thus,SIRT2 was used to modify substrates by truncating the amino acids or lysine side chain of nonapeptide.Finally,two specific and efficient fluorescent probes for SIRT2,ne-D9 and ne-K4a,were developed.Evaluation of the results revealed that ne-K4a based assay was more suitable for modulators screening in vitro,while the other specific substrate ne-D9 was stable in cell lysate and could detect the activity of SIRT2 in the same.In summary,this study presents a novel strategy for detecting SIRT2 activity in vitro and in cell lysate.
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.
