Atropurpuran, a novel diterpene with an unprecedented pentacyclic cage skeleton, from Aconitum hemsleyanum var. atropurpureum

Atropurpuran—missing biosynthetic link leading to the hetidine and arcutine C 20 -diterpenoid alkaloids or an oxidative degradation product?

“…In 2000 and 2001, Saidhhodzhaeva and Bassonova reported the isolation and characterization of two structurally unique alkaloids found in the leaves of Aconitum arcuatum Maxim., arcutine ( 1a ) and arcutinine ( 1b , Figure 1). 1 Until the discovery of atropurpuran ( 2 ) in 2009 by the Wang group, 2 the arcutines ( 1a and 1b ) were the only known secondary metabolites that featured a tetracyclo[5.3.3.0 4,9 .0 4,12 ]tridecane motif. Additionally, these alkaloids are the only diterpenoid alkaloids that possess a bond between C5 and C20 rather than the usual C10–C20 linkage (see hetidine core 3 for numbering).…”

“…2 In their biosynthetic proposal, fragmentation of the C13–C14 bond of 4 would lead to di-aldehyde 5 . A retro-Diels-Alder reaction involving the loss of ethylene would yield cyclohexadienone 6 , which could then be engaged by hydroxide in an oxo-Michael-type addition.…”

Asymmetric baker’s yeast reductions of bridgehead-substituted bicyclo[2.2.2]octane-2,6-dione derivatives followed by conversion into catalytically active BODOLs for the diethylzinc addition to benzaldehyde

“…Bicyclo [2.2.2]octanes are often found as subunits in natural products [1][2][3][4][5][6][7][8] and they are frequently used as important building blocks in total synthesis [9][10][11][12][13][14][15] and as ligands in asymmetric catalysis. [16][17][18][19][20][21][22][23][24][25] New applications for bicyclo [2.2.2]octanes are presented continuously.…”

A Tandem 1,3-H-Shift–6π-Electrocyclization–Cyclic 2-Amido-diene Intramolecular Diels–Alder Cycloaddition Approach to BCD-Ring of Atropurpuran

“…atropurpureum , unveiling an unusual pentacyclic motif that containing two contiguous bicyclo[2.2.2]octanes. 12 Although atropurpuran represents the latest example of unique and brilliant structural topology that Aconitum genus has engineered, examples of diterpenes are rare. Most of them are C 18 , C 19 , and C 20 -diterpenoid alkaloids and possess a superb array of medicinal properties.…”