Heterocyclic marasmane sesquiterpenes

The group of heterocyclic marasmane sesquiterpenes includes hemi-acetals velutinal (7.12), isovellerol (7.11), rubrocinctal A (7.4), and their derivatives and lactones which are unsubstituted or possess up to three hydroxy groups. Velutinal esters 7.28 and 7.30 have already been illustrated. The free hemiacetal velutinal (7.12) does not occur in intact fruiting bodies where, instead, is contained in the form of esters (see above) however, small amounts of 7.12 were detected by tic in a hexane extract of injured L. vellereus within the first minutes after grinding at 4° (7). Moreover, velutinal could be obtained by ethanolysis at 25° of 

The aldehyde rubrocinctal A (7.4), the 12-carboxymethyl ester rubrocinctal B (7.16), and the corresponding 6-oxostearoyl esters 7.27 and 7.31 were isolated from Lactarius rubrocinctus Section Ichorati (2), (69). They are of special interest because they are, along with glutinopallal esters 8.2 and 8.3, the only examples of 12-oxygenated sesquiterpenes isolated from Lactarius species. 

31 5-(6 -oxostearoyloxy) C34H54O6 7 (8)-en 2a,9a-H 12-acid Me ester, 6 -Ketostearoyl-rubrocinctal B L. rubrocinctus (69) 

---

Marasmane sesquiterpenes, possibly resulting from contraction of the cyclobutane ring of the protoilludane skeleton (Scheme 1), can be divided into two groups tricyclic (Part 6) and heterocyclic (tetracyclic) (Part 7). The tricyclic constituents were divided into three subgroups simple marasmanes (6.1-6.8), isomarasmanes (6.9-6.11) and 13-normarasmanes (6.12-6.22). 

---