Stereoselective Total Synthesis of (±)-5-epi-Cyanthiwigin I via an Intramolecular Pauson–Khand Reaction as the Key Step

Abstract

A convenient approach to the construction of the 5-6-7 tricarbocyclic fused core structure of cyanthiwigins via a Co-mediated Pauson-Khand reaction as a key step has been developed. The cyathane core intermediate obtained by this strategy was used in the concise synthesis of (±)-5- epi-cyanthiwigin I. The developed chemistry paves the way for the total synthesis of structurally diverse cyanthiwigins.

Diterpenes Specially Produced by Fungi: Structures, Biological Activities, and Biosynthesis (2010–2020)

“…The cyathane structure is different from the homoverrucosane, mulinane, and valparane diterpenoids which also possess a 5/6/7 tricarbocyclic system [ 48 , 49 ]. The cyathanes are most similar to cyanthiwigins and can be differentiated by the orientation of the angular methyl groups, mainly present in some sponges [ 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ]. These compounds display a diverse range of biological activities, including anticancer, antimicrobial, anti-MRSA (methicillin-resistant Staphylococcus aureus ), anti-inflammatory, anti-proliferative, and nerve growth factor (NGF)-like properties [ 19 , 20 , 60 , 61 ].…”

Application of Pauson–Khand reaction in the total synthesis of terpenes

“…The developed chemistry enables the total synthesis of 5-epi-cyanthiwigin I 257 in seventeen steps and can be used for the total synthesis of other cyanthiwigins (Scheme 20). 177 Naturally occurring compound, ryanodine 184,185 and its hydrolysis product ryanodol 270, 185,186 are among the most highly oxidized diterpenoids reported so far. Ryanodol 270 was isolated from the extracted tropical shrub Ryania speciose Vahl reported by Pepper and Carruth in 1945, 187 and then by other research groups.…”

“…Cyanthiwigins 176 257 contain a cyclohepta[ e ]indene core and structurally belongs to the diverse cyathane class of diterpene. 177 They were isolated from the extract of the marine sponges Epipolasis reiswigi and Mermekioderma styx . Biologically, cyanthiwigins were found being cytotoxic towards A549 lung cancer cells and primary tumor cells.…”

“…The developed chemistry enables the total synthesis of 5- epi -cyanthiwigin I 257 in seventeen steps and can be used for the total synthesis of other cyanthiwigins ( Scheme 20 ). 177 …”

Synthesis of non-natural cyanthiwigin–gagunin hybrids through late-stage diversification of the cyanthiwigin natural product core

“…Noting this limitation along with the structural challenges presented by the molecules, chemists have targeted various members of the cyanthiwigin family for total synthesis. 11,12 To date, ten cyanthiwigins have been prepared, including cyanthiwigins U, W, and Z by Phillips and co-workers; 13 cyanthiwigin AC by Reddy and co-workers; 14…”