The potential of Cyathus africanus for transformation of terpene substrates

Total Synthesis of Stemarene and Betaerene Diterpenoids: Divergent Ring-Formation Strategy and Late-Stage C–H Functionalization

“…Although the C2-oxygenation of (+)-stemar-13-ene (1) 41 is a biosynthetically viable process 27,42,43 to generate (+)-2-oxostemar-13-ene (2), 44 given the high competitiveness of allylic positions (C8 and C17) present in 1 during the C2-H oxygenation with chemical oxidants, we postulated that compound 6 would be a more superior substrate for C2-H oxygenation than 1. The C2-H oxygenations of a less complicated system sclareolide have been well studied in recent years.…”

Stemodane Diterpenes and Diterpenoids: Isolation, Structure Elucidation, Biogenesis, Biosynthesis, Biological Activity, Biotransformations, Metabolites and Derivatives Biological Activity, Rearrangements

“…Finally, very interesting observations were made by Reese and his group in collaboration with Reynolds. It was found that the incubation of (+)-stemodin (1) with Cyathus africanus leads, though in low yield, to (+)-stemodinone (2), while that of (+)-stemodinone (2) leads to (+)-stemodin (1) [76] (Scheme 6). In order to avoid the redox process and to have better substrates for hydroxylation, (+)-stemodinone (2) was deoxygenated to (+)-2-deoxystemodinone (6) and later dehydrated to (19).…”

“…Finally, very interesting observations were made by Reese and his group in collaboration with Reynolds. It was found that the incubation of (+)-stemodin ( 1 ) with Cyathus africanus leads, though in low yield, to (+)-stemodinone ( 2 ), while that of (+)-stemodinone ( 2 ) leads to (+)-stemodin ( 1 ) [ 76 ] ( Scheme 6 ).…”

Stemarane Diterpenes and Diterpenoids

“…Finally, a very interesting observation was made by the Reese group; 12-stemodene 28 , under the conditions the biotransformation by the fungus Cyathus africanus is carried out, not only is oxidized at C(2) but the skeleton is rearranged to the stemarene one giving 2-oxo-13-stemarene 29 (Scheme 3) [38]. In this respect, it should be recalled that stemodane and stemarane diterpenoids were both isolated from Stemodia maritima L. [1,39,40].…”