Isopalhinine A, a Unique Pentacyclic <italic>Lycopodium</italic> Alkaloid from <italic>Palhinhaea cernua</italic>
نویسندگان
چکیده
A new pentacyclic (5/6/6/6/7) Lycopodium alkaloid named isopalhinine A (1), which possesses a sterically congested architecture built with a tricyclo[4.3.1.0]decane (isotwistane) moiety and a 1-azabicyclo[4.3.1]decane moiety, and palhinines B (2) and C (3) were isolated from Palhinhaea cernua. The structure and absolute configuration of 1 were elucidated by a combination of NMR spectra, optical rotation calculation, and X-ray diffraction experiment. A possible biogenetic pathway was also proposed. The Lycopodium alkaloids are a family of structurally diverse natural products from the genus Lycopodium (Lycopodiaceae). The discovery of huperzine A, a potent, selective, and reversible acetylcholinesterase (AChE) inhibitor, has spurred the discoveryof numerous structurally diverse and complex new Lycopodium alkaloids which have proven to be challenging targets for total synthesis. Palhinhaea cernua L. (syn.: Lycopodium cernuum L.), belongingto the familyLycopodiaceae, isa traditionalChinese herbal medicine in the treatment of contusions, scald, and rheumatism. Previously, we reported aLycopodium alkaloid named lycopalhine A (5) which has an intriguing hexacyclic (5/5/5/6/6/6) ring system formed by linkages of C16 C6 and C9 N20 (Figure 1). In our continued research aimed at discoveringstructurally interestingandbioactiveLycopodium alkaloids, isopalhinine A (1), palhinines B (2) and C (3), together with a known compound palhinine A (4), were isolated from the plant. Among them, isopalhinineA (1) is a novel pentacyclic (5/6/6/6/7) Lycopodium alkaloid that possesses a sterically congested architecture built with a tricyclo[4.3.1.0]decane (isotwistane) moiety and a 1-azabicyclo[4.3.1]decane moiety. The functionalized bridged isotwistane system was formed by a unique linkage of C16 C4. Moreover, different from all of the reported naturally occurring fawcettimine-type Lycopodium alkaloids, isopalhinine A (1) has a 1-azabicyclo[4.3.1]decane moiety through a unique N C5 bond. The formation of unique C16 C4 and N C5 bonds in isopalhinine A (1) makes it one of themost sterically congested and structurally complex Lycopodium alkaloids. Kunming Institute of Botany. University of Chinese Academy of Sciences. (1) For recent reviews, see: (a) Ma, X.; Gang, D. R. Nat. Prod. Rep. 2004, 21, 752–772. (b) Hirasawa, Y.; Kobayashi, J.; Morita, H.Heterocycles 2009, 77, 679–729. (c) Kitajima, M.; Takayama, H. Top. Curr. Chem. 2012, 309, 1–31. (2) For selected examples, see: (a) He, J.; Chen, X.-Q.; Li, M.-M.; Zhao, Y.; Xu, G.; Cheng, X.; Peng, L.-Y.; Xie, M.-J.; Zheng, Y.-T.; Wang, Y.-P.; Zhao, Q.-S. Org. Lett. 2009, 11, 1397–1400. (b) Cheng, J.-T.; Liu, F.; Li, X.-N.; Wu, X.-D.; Dong, L.-B.; Peng, L.-Y.; Huang, S.-X.; He, J.; Zhao, Q.-S. Org. Lett. 2013, 15, 2438–2441. (c) Wang X.-J.; Liu,Y.-B.;Li,L.;Yu,S.-S.;Lv,H.-N.;Ma, S.-G.;Bao,X.-Q.;Zhang, D.; Qu, J.; Li, Y. Org. Lett. 2012, 14, 5688–5691. (d) Wang, X.-J.; Zhang, G.-J.; Zhuang, P.-Y.; Zhang, Y.; Yu, S.-S.; Bao, X.-Q.; Zhang, D.; Yuan, Y. H.; Chen, N.-H.; Ma, S.-G.; Qu, J.; Li, Y. Org. Lett. 2012, 14, 2614– 2617. (e) Hirasawa, Y.; Matsuya, R.; Shaari, K.; Lajis, N. H.; Uchiyama, N.; Goda, Y.; Morita, H. Tetrahedron Lett. 2012, 53, 3971–3973. (3) (a) Zhang, X.-C.; Zhang, L.-B. Flora of China; Science Press: Beijing, 2004; Vol. 6, pp 70 73. (b) Zhang, J.-J.; Guo, Z.-J.; Pan, D.-J.; Cai, X. Zhong Cao Yao 1997, 28, 139–140. (4) Dong, L.-B.; Yang, J.; He, J.; Luo, H.-R.; Wu, X.-D.; Deng, X.; Peng, L.-Y.; Cheng, X.; Zhao, Q.-S. Chem. Commun. 2012, 48, 9038– 9040. (5) Zhao, F.-W.; Sun, Q.-Y.; Yang, F.-M.; Hu, G.-W.; Luo, J.-F.; Tang, G.-H.; Wang, Y.-H.; Long, C.-L.Org. Lett. 2010, 12, 3922–3925.
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متن کاملLycopalhine A, a novel sterically congested Lycopodium alkaloid with an unprecedented skeleton from Palhinhaea cernua.
A novel sterically congested Lycopodium alkaloid named lycopalhine A (1) that possesses a fused hexacyclic (5/5/5/6/6/6) ring system comprising a 5,9-diaza-tricyclo[6.2.1.0(4,9)]undecane moiety and a tricyclo[5.2.1.0(4,8)]decane moiety was isolated from Palhinhaea cernua L. The structure and absolute configuration were determined by spectroscopic and computational methods.
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