Protoilludane biosynthesis

Scheme 23. A schematic representation of the postulated involvement of a protoilludane intermediate (213) in the biosynthesis of various sesquiterpenoid...

Furantriol (18.27), isolated from L. mitissimus (84), is one of the few lactarane sesquiterpenes in which one of the gem-methyl groups at C-11 is oxidized and it was chemically correlated (82) with lactarorufin B (11.71), another example of this kind. The Polish authors suggested that lactone 11.71 was enzymatically formed from furan 18.27, and that a C-15 oxidized sesquiterpene of the velutinal type was the common precursor of both compounds in the mushroom (84). Actually, the possibility for the C-15 methyl group to be oxidized at an early stage of the lactarane biosynthesis seems to be confirmed by the recent finding of C-15 hydroxylated protoilludane sesquiterpenoids (5.1 and 5.2) in L. violascens (23) (Table 5). 

The proposed intermediacy of humulene (218) in the biosynthesis of sesquiterpenoids belonging to various structural groups (caryophyllane, protoilludane, etc.)... 

A protoilludane intermediate (225) (c/. Vol. 4, p. 113) has been implicated in the biosynthesis of protoilludane, illudane, illudalane, and marasmane sesquiterpenoids... 

C18H20O5, Mr 316.35, yellow cryst., mp. 174-176 °C, [a]j> -187.1 ° (CHCI3). An antibacterially and cytotox-ically active sesquiterpenoid of the protoilludane type from mycelia cultures of Lentinellus omphalodes and L. ursinus (Basidiomycetes). The biosynthesis probably involves condensation of malonic acid with a pro-toilludane aldehyde ( Armillaria sesquiterpenoids). Lit. Z. Naturforsch. C 43, 177 (1988). - [CAS II52I9-90-4]... 

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