Ethyl 4,4,4-trifluoro-3-oxo-butyrate reacted with 2,6-dimethyl-3,5-diacetyl-pyridine 1 in the presence of NaOC2H5 at 0 ℃ to give 2,6-dimethyl-3,5-bis（4,4,4-trifluoro-1,3-oxo-butyl）-pyridine （2a） in good yield. Cy...Ethyl 4,4,4-trifluoro-3-oxo-butyrate reacted with 2,6-dimethyl-3,5-diacetyl-pyridine 1 in the presence of NaOC2H5 at 0 ℃ to give 2,6-dimethyl-3,5-bis（4,4,4-trifluoro-1,3-oxo-butyl）-pyridine （2a） in good yield. Cyclization reaction of 2a and aryl imidoyl chlorides 5a--5i, obtained from chlorination of aryl oximes with N-chlorosuccimide, afforded 2,6-dimethyl-3,5-bis[（3-aryl-5-trifluoromethyl）-isoxazol-4-carbonyl]-pyridine derivatives 6a=6i.展开更多
Ultrasonically assisted nitration reactions (USANR) with anilides, moderately activated and non-activated aromatic compounds underwent smoothly and afforded good yields of products with high regio selectivity. Observe...Ultrasonically assisted nitration reactions (USANR) with anilides, moderately activated and non-activated aromatic compounds underwent smoothly and afforded good yields of products with high regio selectivity. Observed longer reaction times (6 - 8 hrs.) in metal catalyzed reactions reduced to (1 - 2 hrs.) under sonication. When ortho position is blocked para derivatives are obtained, and ortho nitro products are obtained when para position is blocked. In case of USANR of aromatic carbonyl and related compounds the effect of sonication is much more effective. The reactions could be completed only in few minutes.展开更多
Homobrassinolide (2) and (22S, 23S)-22,23-epi-homobrassinolide (4) were synthesized fromstigmasterol in seven steps respectively in 4.7% and 24.1% overall yields. The ratio of 2 to 4is 1:5. The key step is the highly ...Homobrassinolide (2) and (22S, 23S)-22,23-epi-homobrassinolide (4) were synthesized fromstigmasterol in seven steps respectively in 4.7% and 24.1% overall yields. The ratio of 2 to 4is 1:5. The key step is the highly regioselective formation of the B--homo-7-oxa-lactone ringby oxidation of an enol silyl ether with 3--chloro-peroxybenzoic acid.展开更多
In search of novel herbicides with high activity, a series of 2-arylthio-1, 2, 4-triazolo[1,5-a] pyrimidines (3) were synthesized by cyclization of 5-amino-3-arylthio-1,2,4-triazoles with 1,3-diketones or by the nucle...In search of novel herbicides with high activity, a series of 2-arylthio-1, 2, 4-triazolo[1,5-a] pyrimidines (3) were synthesized by cyclization of 5-amino-3-arylthio-1,2,4-triazoles with 1,3-diketones or by the nucleophilic substitution of substituted thiophenols with 2-methylsulfonyl-1, 2, 4-triazolo [1, 5-a]-pyrimidine. The structures of all compounds prepared were confirmed by H-1 NMR and MS spectroscopy along with elemental analyses. Preliminary bioassays indicated that some of the compounds 3 had good herbicidal activity against rape. In addition, the regioselectivity in the reaction of 5-amino-3-substituted arylthio-1,2, 4-triazoles with benzoylacetone was studied.展开更多
Allylic amines and 1,3-oxazinanes are valuable molecular skeletons in organic synthesis and pharmaceutical industry.A straightforward way to such two types of compounds by solvent-controlled rare-earth metal Lewis aci...Allylic amines and 1,3-oxazinanes are valuable molecular skeletons in organic synthesis and pharmaceutical industry.A straightforward way to such two types of compounds by solvent-controlled rare-earth metal Lewis acid-catalyzed transformations of 2-(hetero)aryl-N-sulfonylazetidines:the ring-opening isomerization of azetidines to allylic amines and the annulation of azetidines with aldehydes to 1,3-oxazinanes are reported.These two reactions feature scalability,low catalyst loading,mild reaction conditions,excellent yields and regioselectivity with demonstrated utility in three-step product transformations to naftifine,abamine and abamine SG.展开更多
By the cyclization of 4,4-dimethylcyclohexane-1,3-dione with different aromatic aldehydes, the xanthene regio- isomers were obtained. The diversity of xanthene isomers could be determined. The electronic and steric ef...By the cyclization of 4,4-dimethylcyclohexane-1,3-dione with different aromatic aldehydes, the xanthene regio- isomers were obtained. The diversity of xanthene isomers could be determined. The electronic and steric effects on aromatic aldehydes could be observed.展开更多
This paper reports the primary results of the study. on the regioselectivity of the cyclization reaction of 5-amino-1, 2, 4-triazole and its analogues until asym-1, 3-dicarbonyl compounds. The mechanistic explanation ...This paper reports the primary results of the study. on the regioselectivity of the cyclization reaction of 5-amino-1, 2, 4-triazole and its analogues until asym-1, 3-dicarbonyl compounds. The mechanistic explanation for the regioselectivity is presented.展开更多
基金Acknowledgement The authors thank the National Natural Science Foundation of China （NNSFC） （Nos. 21072128, 21272153）, the Key Laboratory of Organofluorine Chemistry, Shanghai Institute of Organic Chemistry for financial support.
文摘Ethyl 4,4,4-trifluoro-3-oxo-butyrate reacted with 2,6-dimethyl-3,5-diacetyl-pyridine 1 in the presence of NaOC2H5 at 0 ℃ to give 2,6-dimethyl-3,5-bis（4,4,4-trifluoro-1,3-oxo-butyl）-pyridine （2a） in good yield. Cyclization reaction of 2a and aryl imidoyl chlorides 5a--5i, obtained from chlorination of aryl oximes with N-chlorosuccimide, afforded 2,6-dimethyl-3,5-bis[（3-aryl-5-trifluoromethyl）-isoxazol-4-carbonyl]-pyridine derivatives 6a=6i.
基金Project supported by the National Natural Science Foundation of Chinathe Foundation of National Key Laboratory of Bioorganic Natural Product Chemistry of China.
文摘Linalyl alkyl or aryl carbinols were regioselectively synthesized by the reaction of geranyl bromide and powdered tin with aldehydes and ketones.
文摘Ultrasonically assisted nitration reactions (USANR) with anilides, moderately activated and non-activated aromatic compounds underwent smoothly and afforded good yields of products with high regio selectivity. Observed longer reaction times (6 - 8 hrs.) in metal catalyzed reactions reduced to (1 - 2 hrs.) under sonication. When ortho position is blocked para derivatives are obtained, and ortho nitro products are obtained when para position is blocked. In case of USANR of aromatic carbonyl and related compounds the effect of sonication is much more effective. The reactions could be completed only in few minutes.
文摘Homobrassinolide (2) and (22S, 23S)-22,23-epi-homobrassinolide (4) were synthesized fromstigmasterol in seven steps respectively in 4.7% and 24.1% overall yields. The ratio of 2 to 4is 1:5. The key step is the highly regioselective formation of the B--homo-7-oxa-lactone ringby oxidation of an enol silyl ether with 3--chloro-peroxybenzoic acid.
基金Project Supported by the National Natural Science Foundation of China (No: 29802002), the Natural Science Foundation of Hubei Province and the Dawn Plan of Science and Technology for Young Scientists of Wuhan City.
文摘In search of novel herbicides with high activity, a series of 2-arylthio-1, 2, 4-triazolo[1,5-a] pyrimidines (3) were synthesized by cyclization of 5-amino-3-arylthio-1,2,4-triazoles with 1,3-diketones or by the nucleophilic substitution of substituted thiophenols with 2-methylsulfonyl-1, 2, 4-triazolo [1, 5-a]-pyrimidine. The structures of all compounds prepared were confirmed by H-1 NMR and MS spectroscopy along with elemental analyses. Preliminary bioassays indicated that some of the compounds 3 had good herbicidal activity against rape. In addition, the regioselectivity in the reaction of 5-amino-3-substituted arylthio-1,2, 4-triazoles with benzoylacetone was studied.
文摘Allylic amines and 1,3-oxazinanes are valuable molecular skeletons in organic synthesis and pharmaceutical industry.A straightforward way to such two types of compounds by solvent-controlled rare-earth metal Lewis acid-catalyzed transformations of 2-(hetero)aryl-N-sulfonylazetidines:the ring-opening isomerization of azetidines to allylic amines and the annulation of azetidines with aldehydes to 1,3-oxazinanes are reported.These two reactions feature scalability,low catalyst loading,mild reaction conditions,excellent yields and regioselectivity with demonstrated utility in three-step product transformations to naftifine,abamine and abamine SG.
文摘By the cyclization of 4,4-dimethylcyclohexane-1,3-dione with different aromatic aldehydes, the xanthene regio- isomers were obtained. The diversity of xanthene isomers could be determined. The electronic and steric effects on aromatic aldehydes could be observed.
文摘This paper reports the primary results of the study. on the regioselectivity of the cyclization reaction of 5-amino-1, 2, 4-triazole and its analogues until asym-1, 3-dicarbonyl compounds. The mechanistic explanation for the regioselectivity is presented.
