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排序方式: 共有103条查询结果,搜索用时 234 毫秒
1.
Giang Truong Nguyen Prof. Dr. Liviu Ungur 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(30):e202200227
Employing radical bridges between anisotropic metal ions has been a viable route to achieve high-performance single-molecule magnets (SMMs). While the bridges have been mainly considered for their ability to promote exchange interactions, the crystal-field effect arising from them has not been taken into account explicitly. This lack of consideration may distort the understanding and limit the development of the entire family. To shed light on this aspect, herein we report a theoretical investigation of a series of N -radical-bridged diterbium complexes. It is found that while promoting strong exchange coupling between the terbium ions, the N -radical induces a crystal field that interferes destructively with that of the outer ligands, and thus reduces the overall SMM behavior. Based on the theoretical results, we conclude that the SMM behavior in this series could be further maximized if the crystal field of the outer ligands is designed to be collinear with that of the radical bridge. This conclusion can be generalized to all exchange-coupled SMMs. 相似文献
2.
It is shown that on the superacid cyclization of esters of bishomobicyclogeranylgeranic and E,E-bishomofarnesic acids fully cyclized hydroxyesters are formed in good yield, while on the interaction of esters of 6-hydroxy- and 6-acyloxy-15-bishomobicyclogeranylgeranic acids with a superacid no carbocyclization takes place. 相似文献
3.
It has been shown that the opening of the cyclopropane ring in (1R, 2S, 7S, 10S, 11R, 12S, 13S)-2,6,6,10,12-pentamethylpentacyclo[10.2.1.01,10.02,7.011,13]pentadecane takes place under the action of fluorosulfonic acid at all three carbon-carbon bonds, but at low temperatures the main isomerization product is (1R, 2S, 7S, 10S, 12S, 13S)-2,6,6,10,12-pentamethyltetracyclo[10.2.1.01,10.02,7]pentadecan-13-ol, and at the ordinary temperature the main products are (1R, 2S, 7S, 11S, 12R, 13R)-2,6,6,11,13-pentamethyltetracyclo[10.2.1.01,10.02,7]pentadeca-9-ene and (1S, 2R, 11S, 12R, 15R)-2,7,7,11,15-pentamethyltetracyclo[10.2.1.02,11.03,8]pentadeca-3(8)-ene.Institute of Chemistry, Moldavian SSR Academy of Sciences, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 497–500, July–August, 1989. 相似文献
4.
The hydrocarbon fractions of the products of the cyclization of manool and sclareol by a mixture of conc. sulfuric and formic or acetic acids have been investigated. It has been established that they contain, in addition to the 8/9-pimaradiene, 8(9)-isopimaradiene, roasadiene, and 13-epirosadiene identified previously, the tetracyclic hydrocarbons (1R, 2S, 7S, 11S, 12R, 13R)-2, 6, 6, 11, 13-pentamethyl-tetracyclo [10.2.1.01.10.02.7] pentadeca-9-ene and (1S, 2R, 11S, 12R, 1R)-2, 7, 7, 11, 15-pentamethyltetracyclo[10.2.1.02.11.03.8] pentadeca(8)-ene.Institute of Chemistry of the Moldavian SSR Academy of Sciences, Kishinev. Translated from Khimiya Prirodnykh Soedinii, No. 5, pp. 719–721, September–October, 1988. 相似文献
5.
Institute of Chemistry, Moldavian SSR Academy of Sciences, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 759–760, September–October, 1988. 相似文献
6.
20-Deoxoluteone has been synthesized from sclareol. Sclareol was brominated with phosphorus tribromide to form a mixture of primary allyl bromides, from which, by the malonic synthesis, a mixture of bicyclogeranylgeranylacetic acids was obtained which was cyclized with fluorosulfonic acid to form a mixture of two diastereomeric -lactones. The predominating lactone was converted by successive reduction with lithium tetrahydroaluminate, oxidation with oxalyl chloride in dimethyl sulfoxide, reaction with methylmagnesium iodide, and oxidation by the chromium trioxide/pyridine complex into 20-deoxyluteone.Institute of Chemistry, Moldavian SSR Academy of Science, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 346–353, May–June, 1990. 相似文献
7.
S. S. Koval’skaya N. G. Kozlov V. Kulcitki A. Aricu N. Ungur 《Russian Journal of Organic Chemistry》2013,49(2):303-311
Sclareol under the mild conditions of Ritter reaction is converted into N,N′-[(8R,13)-labdan-14(15)-ene-8,13-diyl]diacetamides stereoisomeric at the C13 atom possessing the unrearranged skeleton of the initial diol. One of the minor reaction products is the N-[(8α,13)-epoxylabdan-14-yl]acetamide whose formation requires the intermediate cyclization of the sclareol. Under more severe conditions and at the reversed order of the reagents addition the prevailing components of the reaction mixture are cyclized and rearranged N-[(8α,14)-epoxy-16(13→14)-abeo-labdan-13-yl]acetamides stereoisomeric at the C13 atom, and minor compounds, (8α,13)-epoxy-16(13→14)-abeo-labdan-12(13)-ene and (8α,14)-epoxy-16(13→4)-abeo-labdan-12(13)-ene. 相似文献
8.
Morarescu O. Grinco M. Kulcitki V. Barba A. Garbuz O. Gulea A. Ungur N. 《Russian Journal of Organic Chemistry》2021,57(12):1931-1939
Russian Journal of Organic Chemistry - A procedure has been developed for the synthesis of highly functionalized tetracyclic diterpenoids from natural ent-kaur-16-en-19-oic acid under modified... 相似文献
9.
20-Deoxoluteone has been synthesized from sclareol. Sclareol was brominated with phosphorus tribromide to form a mixture of
primary allyl bromides, from which, by the malonic synthesis, a mixture of bicyclogeranylgeranylacetic acids was obtained
which was cyclized with fluorosulfonic acid to form a mixture of two diastereomeric δ-lactones. The predominating lactone
was converted by successive reduction with lithium tetrahydroaluminate, oxidation with oxalyl chloride in dimethyl sulfoxide,
reaction with methylmagnesium iodide, and oxidation by the chromium trioxide/pyridine complex into 20-deoxyluteone.
Institute of Chemistry, Moldavian SSR Academy of Science, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 3,
pp. 346–353, May–June, 1990. 相似文献
10.
It has been shown that the opening of the cyclopropane ring in (1R, 2S, 7S, 10S, 11R, 12S, 13S)-2,6,6,10,12-pentamethylpentacyclo[10.2.1.01,10.02,7.011,13]pentadecane takes place under the action of fluorosulfonic acid at all three carbon-carbon bonds, but at low temperatures the main isomerization product is (1R, 2S, 7S, 10S, 12S, 13S)-2,6,6,10,12-pentamethyltetracyclo[10.2.1.01,10.02,7]pentadecan-13-ol, and at the ordinary temperature the main products are (1R, 2S, 7S, 11S, 12R, 13R)-2,6,6,11,13-pentamethyltetracyclo[10.2.1.01,10.02,7]pentadeca-9-ene and (1S, 2R, 11S, 12R, 15R)-2,7,7,11,15-pentamethyltetracyclo[10.2.1.02,11.03,8]pentadeca-3(8)-ene. 相似文献