Total syntheses of lindenane-type sesquiterpenoids: (±)-chloranthalactones A, B, F, (±)-9-hydroxy heterogorgiolide, and (±)-shizukanolide E

Atypical Lindenane-Type Sesquiterpenes from Lindera myrrha

“…In these conditions, the recorded ECD spectra provided no clear-cut match, irrespective of the absolute configuration used in TDDFT. This observation is in line with precedents having outlined the inherent instability of lindenane ring system [16,17], which was occasionally reported in the course of former phytochemical investigations [18]. Despite the lack of spectroscopic evidence, the consensual β-orientation of both the methyl and cyclopropyl functions not only in Lindera species [2], but also within the Chloranthaceae plants that produce a much higher number of these sesquiterpenes [19,20], gave strong support to the preferred absolute configuration depicted in Figure 1.…”

A unified strategy toward total syntheses of lindenane sesquiterpenoid [4 + 2] dimers

“…In accordance with reported protocols 6 , 46 can be transformed into sarcandrolide J ( 6 ) and shizukaol D ( 7 ), two [4 + 2] lindenane dimers of type 2 44–47 . Similarly, compound 48 was synthesized in a moderate yield (43%) by heating the mixture of 25 and chloranthalactone A ( 47 ), synthesized from verbenone as well 17,18,23–25 . After deprotection of the MOM ether and oxidative elaboration of the furan ring, shizukaol A ( 4 ), a [4 + 2] lindenane dimer of type 1 48 , was synthesized.…”

Total Syntheses of Sarcandrolide J and Shizukaol D: Lindenane Sesquiterpenoid [4+2] Dimers

“…The synthetically challenging molecular architecture and appealing bioactivities made these dimeric sesquiterpenoids popular synthetic targets. However, no total synthesis leading to these [4+2] dimers has been achieved yet, whereas elegant total syntheses of lindenane monomers and a sole [2+2] dimer named chloranthalactone F,, as well as synthetic study toward the [4+2] dimers, are reported. Herein we report the total synthesis of two representative molecules of this family, shizukaol D ( 4 ) and sarcandrolide J ( 5 ).…”

“…Protection of the primary alcohol with BPSCl and ketal removal furnished 17 , which was subjected to aldol reaction to afford 18 . Acetylation of the tertiary alcohol,, and the subsequent DBU/LiBr elimination smoothly produced 23 . The presence of LiBr is crucial to avoid the competitive formation of 20′ from 20 .…”