27498-90-4Relevant articles and documents
Unified Total Synthesis of Stemoamide-Type Alkaloids by Chemoselective Assembly of Five-Membered Building Blocks
Yoritate, Makoto,Takahashi, Yoshito,Tajima, Hayato,Ogihara, Chisato,Yokoyama, Takashi,Soda, Yasuki,Oishi, Takeshi,Sato, Takaaki,Chida, Noritaka
, p. 18386 - 18391 (2017)
A unified total synthesis of stemoamide-type alkaloids is reported. Our synthetic approach features the chemoselective convergent assembly of five-membered building blocks via stemoamide as the common precursor to tetracyclic natural products. The synthesis consists of two successive coupling reactions of the three five-membered building blocks. The first coupling reaction is the vinylogous Michael addition/reduction sequence, which enables the gram-scale synthesis of stemoamide. The second coupling reaction is a chemoselective nucleophilic addition to stemoamide. While the lactone-selective nucleophilic addition to stemoamide affords saxorumamide and isosaxorumamide, the lactam-selective reductive nucleophilic addition leads to the formation of stemonine. Both chemoselective nucleophilic additions enable direct modification of stemoamide, resulting in highly concise and efficient total syntheses of the stemoamide-type alkaloids.
Lactam Strategy Using Amide-Selective Nucleophilic Addition for Quick Access to Complex Amines: Unified Total Synthesis of Stemoamide-Type Alkaloids
Chida, Noritaka,Ogihara, Chisato,Oishi, Takeshi,Sato, Takaaki,Shibuya, Kana,Soda, Yasuki,Sugiyama, Yasukazu,Tajima, Hayato,Takahashi, Yoshito,Yokoyama, Takashi,Yoritate, Makoto
, p. 278 - 287 (2022/03/17)
Our research group has been exploring a lactam strategy for the concise total synthesis of complex alkaloids. In this article, we report full details of the unified total synthesis of stemoamide-type alkaloids by chemoselective assembly of five-membered rings based on the lactam strategy. First, the concise and gram-scale synthesis of tricyclic stemoamide was achieved by vinylogous Michael addition-reduction sequence of an unsaturated γ-lactam with an unsaturated γ-lactone, followed by N-alkylation to form the seven-membered ring. From stemoamide as a common intermediate, chemoselective nucleophilic addition of unsaturated lactone derivatives provides tetracyclic natural products. While stemonine is obtained by an Ir-catalyzed lactam-selective reductive Mannich reaction, saxorumamide and isosaxorumamide are produced through the lactone-selective nucleophilic addition of the lithiated 2- silyl furan. The developed conditions for the lactam-selective nucleophilic reactions are highly general, and were found to be applicable to the total synthesis of pentacyclic stemocochinin and isostemocochinin. The strategy enables the concise and unified total synthesis of tricyclic, tetracyclic and pentacyclic stemoamide-type alkaloids within 12 steps from a commercially available compound.
Tailored Synthesis of Skeletally Diverse Stemona Alkaloids through Chemoselective Dyotropic Rearrangements of β-Lactones
Guo, Zhen,Bao, Ruiyang,Li, Yuanhe,Li, Yunshan,Zhang, Jingyang,Tang, Yefeng
, p. 14545 - 14553 (2021/05/31)
The collective synthesis of skeletally diverse Stemona alkaloids featuring tailored dyotropic rearrangements of β-lactones as key elements is described. Specifically, three typical 5/7/5 tricyclic skeletons associated with stemoamide, tuberostemospiroline and parvistemonine were first accessed through chemoselective dyotropic rearrangements of β-lactones involving alkyl, hydrogen, and aryl migration, respectively. By the rational manipulation of substrate structures and reaction conditions, these dyotropic rearrangements proceeded with excellent efficiency, good chemoselectivity and high stereospecificity. Furthermore, several polycyclic Stemona alkaloids, including saxorumamide, isosaxorumamide, stemonine and bisdehydroneostemoninine, were obtained from the aforementioned tricyclic skeletons through late-stage derivatizations. A novel visible-light photoredox-catalyzed formal [3+2] cycloaddition was also developed, which offers a valuable tool for accessing oxaspirobutenolide and related scaffolds.
Total synthesis of (-)-stemonine
Williams, David R.,Shamim, Khalida,Reddy, Jayachandra P.,Amato, George S.,Shaw, Stephen M.
, p. 3361 - 3364 (2007/10/03)
(Matrix Presented) An enantioselective total synthesis of (-)-stemonine (1) is reported via a convergent assembly of the acyclic precursor 2. Key transformations include a Staudinger-aza-Wittig reaction to form the central perhydroazepine ring system and
