Synthesis of New, Unnatural Macrocyclic Trichothecenes: 3‐isoverrucarin A ((1″‐ O )(3→4) abeo ‐verrucarin A), verrucinol, and verrucene. 46th Communication on verrucarins and roridins

A new unnatural macrocyclic trichothecene, an analogue of verrucarine A ( 1 ), which was named 3‐Isoverrucarin A ((1″‐ O )(3→4) abeo ‐verrucarin A; 3 ) was synthesized starting from anguidine ( 5 ). The two key reactions were the removal of the 4β‐acetoxy group of anguidine ( 5 ) by a Barton deoxygenation and the final macrolactonization. During the cyclization procedure, two unexpected new macrocyclic by‐products, which were named verrucinol ( 19 ) and verrucene ( 20 ), were formed. They represent novel types of macrocyclic trichothecenes, the macrolidic moiety of verrucene ( 20 ) consisting only of the ( Z,E )‐muconic‐acid residue. The formation of the analogous macrolide 26 of verrucene ( 20 ) was not possible, probably because the ring strain is too strong.