Highly modified cephalotane-type diterpenoids from Cephalotaxus fortunei var. alpina and C. sinensis

Abstract

Six undescribed cephalotane-type diterpenoids and/or norditerpenoids, ceforloids A–F (1–6), were isolated from Cephalotaxus fortunei var. alpina and C. sinensis. Their structures were elucidated by comprehensive analysis of spectroscopic data. Compound 1 possesses an unprecedented norditerpenoid skeleton featuring an unusual acetophenone moiety, and originated putatively from a disparate biogenetic pathway. Compounds 4 and 5 incorporate a unique 12,13-p-hydroxybenzylidene acetal motif. Compound 6 is a rare cephalotane-type diterpenoid glycoside. Immunosuppressive assays showed that compounds 2 and 6 exhibited mild suppressive activity against the activated T and B lymphocytes proliferation.

Total Synthesis of Cephanolide A and Harringtonolide: A Unified Strategy Connecting Benzenoid and Troponoid Cephalotaxus Diterpenoids

“…Notwithstanding, it was proposed in a recent study by Zhao and Yue to be a biosynthetic intermediate accounting for the formation of a newly discovered 12acyl benzenoid Cephalotaxus diterpenoid skeleton. 22 To explore the benzenoid-to-troponoid ring expansion, our initial studies selected 2,4-dimethyl phenol 22 a model substrate, in mimicking cephanolide A (4) where one of the ortho position of phenol been occupied by Me and the other by H. As illustrated in Figure 3A, 22 was first converted to the corresponding 4-quinol methyl ether 23 in 58% yield. In general, the BCS reaction has been well explored for ring expansion of saturated ketones.…”