Trichothecane sesquiterpenes

From a structural standpoint, these compounds consist of a trichothecane sesquiterpene diol linked through ester bonds to a diacid derived from esterification of the ( )-acid of a (Z, )-muconic acid with a 5-hydroxypentanoic acid segment (containing various substitution patterns). As the synthesis of the sesquiterpene diol unit is beyond the scope of this chapter, we have limited discussion to the methods employed for formation of the macrocyclic ring of these substances. Papers concerning the construction of the various trichothecane diol systems may be found by consulting the references cited in this section. 

Both 1,4- and 1,5-hydrogen rearrangements have been discovered in the biosynthesis of sesquiterpenes and diterpenes. A 1,4-hydrogen transfer occurs in the formation of the bicarbocyclic nucleus of the trichothecane sesquiterpenes, presumably via the parent hydrocarbon trichodiene 35, 207—209). The biosynthesis of helicobasidine, a closely related cuparene-type sesquiterpene, also has a 1,4-hydrogen rearrangement step 210). 

Trichothecenes from Pusarium, Stachybotrys, and Trichoderma, among others. Note Trichothecenes include sesquiterpenes with a trichothecane skeleton, olefinic groups at C-9 and C-10, and epoxies at C-12 and C-13. Macrocyclic trichothecenes have a carbon chain between C-4 and C-15 in an ester or ether linkage (e.g., T-2 toxin, DON, satratoxins G and H verrucarins B and J, trichoverrins A and B)). 

A total of 217 trichothecenes, based on the sesquiterpene skeleton (1) named trichothecane (4), which replaced the earlier (5) scirpane nomen-clature have now been reported from natural sources. They are made up of 133 (61%) non-macrocyclic and 84 (39%) macrocyclic compounds. Thus, 20 new non-macrocyclic trichothecenes have been isolated since 1995 and 17 new macrocycles since 1991. 

Tori, M. Syntheses of trichothecane-type sesquiterpenes and verrucarins. Yuki Gosei Kagaku Kyokaishi 39, 642 (1981). 

---