Divergent Entry to Walsucochin Nortriterpenoids: Total Syntheses of (±)-Walsucochin A and (±)-Walsucochinoids C–F

Abstract

Nortriterpenoids isolated from Walsura cochinchinensis have attracted much attention from both synthetic and medicinal chemists, yet only recently have efficient synthetic approaches to any members appeared. Shown here is that the common intermediate with a 6/6/5/6-fused tetracyclic ring nucleus can be converted to walsucochin family members. The first total syntheses of (±)-walsucochin A, (±)-walsucochinoids C–F, and their analogues were achieved in this work.

The host sex contributes to the endophytic bacterial community in Sargassum thunbergii and their receptacles

“…In addition, there were few degrading bacteria in the receptacles of both sexes, and the degrading bacteria in the male receptacles were the phenol-degrading anaerobic bacterium Thermicanus (Qi, 2021) and the sulfate-degrading bacterium Desulfobulbus (Samain et al, 1986). The female receptacles included the polyethylene degrader Brevibacillus (Stone et al, 2021), biopolymer degrader Tepidisphaera (Jiang et al, 2020) and various macromolecular degraders such as Luteimonas (Lin et al, 2020;Zhou et al, 2021). Moreover, there were alga-soluble bacteria (Muricauda) in the male receptacles (Shi et al, 2012), while there were algicidal bacteria [Kordia (Sohn et al, 2004) and Saprospira (Furusawa et al, 2003)] in the female receptacles.…”

Research progress of meliaceous limonoids from 2011 to 2021

“…Decorating it with Sonogashira or Suzuki cross-coupling afforded the desired (AE)-walsucochin A ( 93) and (AE)-walsucochinoids C-F (97-100) and their analogues. 455 With a similar strategy, the same group has also achieved the total synthesis of (AE)-walsucochin B ( 94), (AE)-walsucochinoids M (107), and N (108). 454 In 2015, Watanabe and coworkers reported an efficient approach to the key Ley's synthetic intermediate by 30 steps for the formal synthesis of azadirachtin.…”

“…Very recently, Xu's group reported a more concise and divergent entry to the walsucochin nortriterpenoids, involving the radical cyclization, benzannulation, and Cu-mediated C–H hydroxylation reaction as the key steps. 454,455 The treatment of franesyl bromide with four steps resulted in the formation of compound I , which was then went through the hydroxylation, benzannulation, and iodination process to generate the common 6/6/5/6-fused tetracyclic ring intermediate (Scheme 14). Decorating it with Sonogashira or Suzuki cross-coupling afforded the desired (±)-walsucochin A ( 93 ) and (±)-walsucochinoids C–F ( 97–100 ) and their analogues.…”

“…Decorating it with Sonogashira or Suzuki cross-coupling afforded the desired (±)-walsucochin A ( 93 ) and (±)-walsucochinoids C–F ( 97–100 ) and their analogues. 455 With a similar strategy, the same group has also achieved the total synthesis of (±)-walsucochin B ( 94 ), (±)-walsucochinoids M ( 107 ), and N ( 108 ). 454…”