Progress in structure, synthesis and biological activity of natural cephalotane diterpenoids

Cephalotane‐Type Norditerpenoids from Cephalotaxus fortunei var. alpina

“…The major difference was the presence of an oxygenated methine group ( δ H 5.59, d, J = 4.1 Hz; δ C 82.4) in 6 replacing CH 2 ‐20 in 3 . To satisfy the IDH requirement, the presence of an additional 3,20‐ether bridge, that occurs commonly among previously reported cephalotane‐type norditerpenoids, [ 9 ] was envisaged, which was confirmed by the HMBC correlation (Figure S5A, Supporting Information) from H‐20 to C‐3. The structure of 6 was further corroborated by comprehensive analysis of its 2D NMR data (Figure S5, Supporting Information).…”

“…Afterwards, ca . 70 derivatives comprising six types of rearranged carbon skeletons were reported successively, [ 9 ] some of which exhibited potent anti‐inflammatory activities [ 5 ] and inhibition of the NF‐κB signaling pathway, [ 5,10 ] and have garnered a fair amount of attention from the synthetic community. [ 11‐17 ] As part of our continuing search for structurally intriguing and/or biologically significant cephalotane diterpenoids/norditerpenoids from Cephalotaxus species, [ 8,10,18‐21 ] nine new cephalotane‐type norditerpenoids ( 1 — 9 ) and two known analogues ( 10 and 11 ) (Figure 1) were isolated from the seeds of C. fortunei var.…”

Recent Advances in the Total Synthesis of Cephalotane-Type Norditerpenoids from Cephalotaxus sinensis

“…According to Figure 3, there are three series of natural products with cephalotane-type skeleton, such as cephanolides A-D (3-6), cephalotanins A-D (7-10) and cephalodiones A-D (11)(12)(13)(14). Because of the prevalence of a contracted A-ring, these could be named as norditerpenoids, whereas cephanolides A-C are the cephalotane-type dinorditerpenoids [23] . Cephanolides A-D and cephalotanins A-D were isolated from Cephalotaxus sinensis by Yue in 2017 [24] and 2016 [5] , whereas cephalodiones A-D were isolated from seeds of C. fortunei var.…”

“…Among these, A-ring is a benzene ring in the cephanolides A-D, whereas an unsaturated six-membered ring in the novel norditerpenoid cephalotanins. The cephalotanin A differs from cephalotanin B, C, and D based on the unique trilactones skeleton, a bicycle[4,1,0]hepta-2,4-dien-7-one segment [23] , and a tertiary alcohol and methyl ester in the left, respectively. Plausible biosynthesis pathways [26,5] toward cephanolides A-D (3-6) and cephalotanins A-D (7-10) are suggested in Scheme 1.…”

“…It has attracted widespread attention from synthetic chemists due to unique structural characteristics of cephanolides while the synthesis of cephalotanins A-D is yet to be reported. Although there are already several overviews that summarize various aspects of the cephanolides class, the recent surge in completed total syntheses of members of this family demands an updated review [23,22] .…”