Sulfated tin oxide (STO) has been found to be an efficient reusable solid superacid catalyst for C3-alkylation and O-alkylation of 4-hydroxycoumarins with benzylic, allylic alcohols/and corresponding acetates respecti...Sulfated tin oxide (STO) has been found to be an efficient reusable solid superacid catalyst for C3-alkylation and O-alkylation of 4-hydroxycoumarins with benzylic, allylic alcohols/and corresponding acetates respectively, in acetic acid under reflux conditions with good yield of products.展开更多
A facile procedure for the synthesis of 3-（2′-amino-3′-cyano-4′-arylpyrid-6′-yl） coumarins are being reported starting from 3- acetylcoumarin, aromatic aldehydes and malononitrile. The reactions were carried out...A facile procedure for the synthesis of 3-（2′-amino-3′-cyano-4′-arylpyrid-6′-yl） coumarins are being reported starting from 3- acetylcoumarin, aromatic aldehydes and malononitrile. The reactions were carried out on microwave irradiation in good yield with short time and easy work-up. The structures of all the compounds have been confirmed on the basis of their analytical, IR, ^1H NMR, and mass spectral data.展开更多
Tetracyclic coumarins are a class of important compounds with diverse and superior pharmacolog‐ical activities.However,a direct stereoselective method from simple and readily‐made coumarins derivatives remains chall...Tetracyclic coumarins are a class of important compounds with diverse and superior pharmacolog‐ical activities.However,a direct stereoselective method from simple and readily‐made coumarins derivatives remains challenging due to the inertness of coumarins as dienophiles.Herein,we de‐velop a decarboxylative asymmetric[4+2]cycloaddition of 3‐cyanocoumarins with vinyl benzoxa‐zinones,affording the coumarin‐derived condensed rings bearing three continuous stereocenters in high yields with excellent diastereoselectivities(>20/1 d.r.)and enantioselectivities(up to 99%ee).This direct enantioselective reaction was achieved by a Pd(0)/Cu(I)bimetallic catalytic system.The mechanism studies indicated that the synergistic activation effect,in which chiral Cu(I)as an availa‐ble Lewis acid catalyst activates 3‐cyanocoumarin and chiral Pd(0)complex activates benzoxazi‐none by the formation ofπ‐allyl‐palladium intermediate,plays an important role on the stereoselec‐tive control.The current work provides a new activation modes of Cu catalyst in the Pd/Cu bimetal‐lic catalytic system.展开更多
Several new pyrazolo[4,3-b] pyridines 7a, b were prepared by reacting arylidenemalononitriles 1a, c or 1i, j with 4-nitrosoantipyrine 4. Reacting 1a, b, d with 4-azidomethylcarbonylantipyrine 8 give 2-aminopyrrole 14....Several new pyrazolo[4,3-b] pyridines 7a, b were prepared by reacting arylidenemalononitriles 1a, c or 1i, j with 4-nitrosoantipyrine 4. Reacting 1a, b, d with 4-azidomethylcarbonylantipyrine 8 give 2-aminopyrrole 14. Pyrano[3,2-c] quinolines 20a, b and 23 were obtained by reacting 4-hydroxyquinoline 15 with 1g, h, 2b respectively. Reaction of 1 with naphthalenediols 24, 27 and 29 yield naphthodipyrans 26a, b, 28a, b and 30a。展开更多
Ethyl ester of 5,7-dimethyl coumarin-4-acetic acid has been synthesized from 3,5-Xylenol in a two step sequence of reaction involving Pechmann cyclisation and acid catalyzed esterification. The title compound 2 crysta...Ethyl ester of 5,7-dimethyl coumarin-4-acetic acid has been synthesized from 3,5-Xylenol in a two step sequence of reaction involving Pechmann cyclisation and acid catalyzed esterification. The title compound 2 crystallizes in Monoclinic form, space group P 1 21/c 1, with a = 8.6248(4) ?, b = 18.9103(8) , c = 8.4204(4)?, β = 101.241(2)?, V = 1347.00(11) ?, D cal = 1.283 Mg/cm3, Z = 4. The molecule is stabilized by intermolecular C-H … O bonds.展开更多
以间苯二酚和乙酰乙酸乙酯为原料,氨基磺酸为催化剂,超声波辐射下合成了7-羟基-4-甲基香豆素,其结构经IR和1 H NMR表征。考察了超声波辐射功率和辐射时间及催化剂用量等因素对反应的影响。结果表明,在80 W辐射反应40min,间苯二酚11g(0.1...以间苯二酚和乙酰乙酸乙酯为原料,氨基磺酸为催化剂,超声波辐射下合成了7-羟基-4-甲基香豆素,其结构经IR和1 H NMR表征。考察了超声波辐射功率和辐射时间及催化剂用量等因素对反应的影响。结果表明,在80 W辐射反应40min,间苯二酚11g(0.1mol),n(间苯二酚)∶n(乙酰乙酸乙酯)∶n(氨基磺酸)=1.0∶1.1∶0.1条件下,7-羟基-4-甲基香豆素的收率到达95%以上。展开更多
分别制备了4种H2SO4-SiO2。以H2SO4-SiO2为催化剂,乙酰乙酸乙酯和间苯二酚为原料,通过Pechmann反应,在无溶剂条件下,催化合成了7-羟基-4-甲基香豆素。以4种不同H2SO4-SiO2、催化剂用量、反应时间、反应温度和反应原料的物质的量比设计...分别制备了4种H2SO4-SiO2。以H2SO4-SiO2为催化剂,乙酰乙酸乙酯和间苯二酚为原料,通过Pechmann反应,在无溶剂条件下,催化合成了7-羟基-4-甲基香豆素。以4种不同H2SO4-SiO2、催化剂用量、反应时间、反应温度和反应原料的物质的量比设计了五因素四水平的正交试验,得到负载硫酸催化反应的最佳条件:n(H2SO4)∶n(Si)=0.75∶1,n(间苯二酚)∶n(乙酰乙酸乙酯)=1∶1,催化剂用量0.35 g(间苯二酚0.04 mol),反应时间95 m in,反应温度105℃,最佳条件下产品收率为72.4%。展开更多
文摘Sulfated tin oxide (STO) has been found to be an efficient reusable solid superacid catalyst for C3-alkylation and O-alkylation of 4-hydroxycoumarins with benzylic, allylic alcohols/and corresponding acetates respectively, in acetic acid under reflux conditions with good yield of products.
基金the Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials for financial support(No.JSKC07041).
文摘A facile procedure for the synthesis of 3-（2′-amino-3′-cyano-4′-arylpyrid-6′-yl） coumarins are being reported starting from 3- acetylcoumarin, aromatic aldehydes and malononitrile. The reactions were carried out on microwave irradiation in good yield with short time and easy work-up. The structures of all the compounds have been confirmed on the basis of their analytical, IR, ^1H NMR, and mass spectral data.
文摘Tetracyclic coumarins are a class of important compounds with diverse and superior pharmacolog‐ical activities.However,a direct stereoselective method from simple and readily‐made coumarins derivatives remains challenging due to the inertness of coumarins as dienophiles.Herein,we de‐velop a decarboxylative asymmetric[4+2]cycloaddition of 3‐cyanocoumarins with vinyl benzoxa‐zinones,affording the coumarin‐derived condensed rings bearing three continuous stereocenters in high yields with excellent diastereoselectivities(>20/1 d.r.)and enantioselectivities(up to 99%ee).This direct enantioselective reaction was achieved by a Pd(0)/Cu(I)bimetallic catalytic system.The mechanism studies indicated that the synergistic activation effect,in which chiral Cu(I)as an availa‐ble Lewis acid catalyst activates 3‐cyanocoumarin and chiral Pd(0)complex activates benzoxazi‐none by the formation ofπ‐allyl‐palladium intermediate,plays an important role on the stereoselec‐tive control.The current work provides a new activation modes of Cu catalyst in the Pd/Cu bimetal‐lic catalytic system.
文摘Several new pyrazolo[4,3-b] pyridines 7a, b were prepared by reacting arylidenemalononitriles 1a, c or 1i, j with 4-nitrosoantipyrine 4. Reacting 1a, b, d with 4-azidomethylcarbonylantipyrine 8 give 2-aminopyrrole 14. Pyrano[3,2-c] quinolines 20a, b and 23 were obtained by reacting 4-hydroxyquinoline 15 with 1g, h, 2b respectively. Reaction of 1 with naphthalenediols 24, 27 and 29 yield naphthodipyrans 26a, b, 28a, b and 30a。
文摘Ethyl ester of 5,7-dimethyl coumarin-4-acetic acid has been synthesized from 3,5-Xylenol in a two step sequence of reaction involving Pechmann cyclisation and acid catalyzed esterification. The title compound 2 crystallizes in Monoclinic form, space group P 1 21/c 1, with a = 8.6248(4) ?, b = 18.9103(8) , c = 8.4204(4)?, β = 101.241(2)?, V = 1347.00(11) ?, D cal = 1.283 Mg/cm3, Z = 4. The molecule is stabilized by intermolecular C-H … O bonds.
文摘以间苯二酚和乙酰乙酸乙酯为原料,氨基磺酸为催化剂,超声波辐射下合成了7-羟基-4-甲基香豆素,其结构经IR和1 H NMR表征。考察了超声波辐射功率和辐射时间及催化剂用量等因素对反应的影响。结果表明,在80 W辐射反应40min,间苯二酚11g(0.1mol),n(间苯二酚)∶n(乙酰乙酸乙酯)∶n(氨基磺酸)=1.0∶1.1∶0.1条件下,7-羟基-4-甲基香豆素的收率到达95%以上。
文摘分别制备了4种H2SO4-SiO2。以H2SO4-SiO2为催化剂,乙酰乙酸乙酯和间苯二酚为原料,通过Pechmann反应,在无溶剂条件下,催化合成了7-羟基-4-甲基香豆素。以4种不同H2SO4-SiO2、催化剂用量、反应时间、反应温度和反应原料的物质的量比设计了五因素四水平的正交试验,得到负载硫酸催化反应的最佳条件:n(H2SO4)∶n(Si)=0.75∶1,n(间苯二酚)∶n(乙酰乙酸乙酯)=1∶1,催化剂用量0.35 g(间苯二酚0.04 mol),反应时间95 m in,反应温度105℃,最佳条件下产品收率为72.4%。
