Two novel C-nor-B-homo aconane-type diterpenes 4 and 5, featuring a unique eight-membered ring system, were obtained by the treatment of C-nor-C19-diterpenoid alkaloid 3 with HNO2 in 8% and 21% yields, respectively. S...Two novel C-nor-B-homo aconane-type diterpenes 4 and 5, featuring a unique eight-membered ring system, were obtained by the treatment of C-nor-C19-diterpenoid alkaloid 3 with HNO2 in 8% and 21% yields, respectively. Structures of these two compounds were established based on the combination of spectroscopic data, including HRESIMS, 1D and 2D NMR data. A olausible mechanism for the formation of 4 and 5 is also presented.展开更多
Oxidation of 1 with KMnO_4 in acetone-H_2O (1:1) for 1h gave nevadenine 2 (38%). But. 3 was formed in 98% yield when prolonging time and raising temperature (40℃). Reaction of 1 and 10 with Conforth reagent afforded ...Oxidation of 1 with KMnO_4 in acetone-H_2O (1:1) for 1h gave nevadenine 2 (38%). But. 3 was formed in 98% yield when prolonging time and raising temperature (40℃). Reaction of 1 and 10 with Conforth reagent afforded the ketones 11 (55%), 12 (30%), and 13 (13%), 14 (20%). respectively. While oxidation of 7 and 15 with a variety of the oxidizing agents gave 17 only in low 20% of yield besides the minor 16. In addition. 1 was converted to 2 by the fungi Curvularia lunata.展开更多
Treatment of 3-acetylpseudaconie 6 and 3. 13-diacetylyunnaconitine 9 withNBS/acetone-H2O(2:1) at room temperature produced corresponding imine derivatives & and 10.respectively. in good yields. This is a novel si...Treatment of 3-acetylpseudaconie 6 and 3. 13-diacetylyunnaconitine 9 withNBS/acetone-H2O(2:1) at room temperature produced corresponding imine derivatives & and 10.respectively. in good yields. This is a novel simple and convenient method for preparation of theimine compounds.展开更多
Treatment of denudatine 1 with 10% HCl soln. at 45-50℃ for 3 days leads to a pair of epimers 4A and 4B, Structures of 4A and 4B have been elucidated on the basis of chemical and spectral methods.
The reactions of denudatine 1 and diacetyldenudatine 2 with NBS-50% HOAc soln. afforded 4 and 6, respectively, in high yields.Treatment of 6 with (Ac)_2CO-Pyr. gives 7. The structures of 3,6 and 7 were deduced on the ...The reactions of denudatine 1 and diacetyldenudatine 2 with NBS-50% HOAc soln. afforded 4 and 6, respectively, in high yields.Treatment of 6 with (Ac)_2CO-Pyr. gives 7. The structures of 3,6 and 7 were deduced on the basis of spectral and chemical methods.展开更多
A bicyclo[2.2.2]octane C/D ring system, with a lactonic ring at C-8 and C-9, of the atisine-type C20-diterpenoid alkaloids, was successfully synthesized, using an oxidative dearomatization/intramolecular Diels-Alder r...A bicyclo[2.2.2]octane C/D ring system, with a lactonic ring at C-8 and C-9, of the atisine-type C20-diterpenoid alkaloids, was successfully synthesized, using an oxidative dearomatization/intramolecular Diels-Alder reaction.展开更多
基金support for this research was provided from the National Natural Science Foundation of China(No.30472075)the Excellent Ph.D.Dissertation Foundation of China(No.200367).
文摘Two novel C-nor-B-homo aconane-type diterpenes 4 and 5, featuring a unique eight-membered ring system, were obtained by the treatment of C-nor-C19-diterpenoid alkaloid 3 with HNO2 in 8% and 21% yields, respectively. Structures of these two compounds were established based on the combination of spectroscopic data, including HRESIMS, 1D and 2D NMR data. A olausible mechanism for the formation of 4 and 5 is also presented.
基金We thank the National Natural Science Foundation of China !(No. 393707) the Chengdu Diao Pharmaceutical Company for support
文摘Oxidation of 1 with KMnO_4 in acetone-H_2O (1:1) for 1h gave nevadenine 2 (38%). But. 3 was formed in 98% yield when prolonging time and raising temperature (40℃). Reaction of 1 and 10 with Conforth reagent afforded the ketones 11 (55%), 12 (30%), and 13 (13%), 14 (20%). respectively. While oxidation of 7 and 15 with a variety of the oxidizing agents gave 17 only in low 20% of yield besides the minor 16. In addition. 1 was converted to 2 by the fungi Curvularia lunata.
文摘Treatment of 3-acetylpseudaconie 6 and 3. 13-diacetylyunnaconitine 9 withNBS/acetone-H2O(2:1) at room temperature produced corresponding imine derivatives & and 10.respectively. in good yields. This is a novel simple and convenient method for preparation of theimine compounds.
基金We thank the National Natural Science Foundation of China(No.30070888)the Chengdu Diao Pharmaceutical Company for support of this work.
文摘Treatment of lappaconitine 1 with NaIO_4 and Br_2-HOAc at room temperature for 7 h afforded smoothly the bromine-containing derivative 4 in 71% yield.
文摘Treatment of denudatine 1 with 10% HCl soln. at 45-50℃ for 3 days leads to a pair of epimers 4A and 4B, Structures of 4A and 4B have been elucidated on the basis of chemical and spectral methods.
文摘The reactions of denudatine 1 and diacetyldenudatine 2 with NBS-50% HOAc soln. afforded 4 and 6, respectively, in high yields.Treatment of 6 with (Ac)_2CO-Pyr. gives 7. The structures of 3,6 and 7 were deduced on the basis of spectral and chemical methods.
基金the financial support provided by the National Science Foundation of China(No.81273387)
文摘A bicyclo[2.2.2]octane C/D ring system, with a lactonic ring at C-8 and C-9, of the atisine-type C20-diterpenoid alkaloids, was successfully synthesized, using an oxidative dearomatization/intramolecular Diels-Alder reaction.
