Fungal Extractives. V. The Stereostructure of two Sesquiterpene Lactones from Lactarius.

The Sesquiterpenes of Lactarius vellereus and Their Role in a Proposed Chemical Defense System

“…Compounds 16 and 17 are new, and their structures could be elucidated by spectral comparison with isovelleral and velleral. The insertion of hydroxyl groups in 16 was clearly indicated, and their position could be established to C-9 by decoupling and nOe experiments. The enzymatic processes that are triggered by an injury may also be affected by a number of conditions.…”

“…Velleral is a new compound, while isovelleral has been isolated previously from extracts of the cultured mycelium of Fomitopsis insularis (17). Extracts made more than 1 h after grinding at 22°w ere, furthermore, shown to contain small amounts of vellerdiol (6), previously prepared by reduction of velleral (16). No traces of other sesquiterpenes were detected by the analytical methods used in this investigation, either in the hexane extracts or in an EtOAc extract made 2.5 min after grinding at 22°, in search for more polar sesquiterpenes.…”

Chemical ecology of fungi

“…For instance, only Lactarius and Russula species seem to use the pungent tasting compounds velleral (42) and isovelleral (43) as defence compounds. 118,119 These secondary metabolites have already been isolated from Lactarius species forty years ago, but it was not until the 1980s that these compounds were identied as extraction artefacts. 88 A TLC comparison of extracts from intact and articially-injured fruiting bodies revealed the presence of stearoylvelutinal (40) as a precursor of the degradation products velutinal (41), velleral (42) and isovelleral (43) in intact fruiting bodies, while injured fruiting bodies only contained the pungent-tasting degradation products (Scheme 2).…”

Fungal extractives. IX. Synthesis of the velleral skeleton and a total synthesis of pyrovellerolactone

“…Drying (Na2S04), evaporation, and chromatography (Si02-CH2C12) gave a yellow oil (22 and the corresponding isomaleimide) (172 mg) which was treated with potassium carbonate solution36 (44%, 15 ml) and dimethoxyethane (3 ml) for 2 hr. Extraction with ether, drying, evaporation, and sublimation (0.1 mm) gave pure 22 (90 mg, 35%): mp 168-169°; ir (KBr) v 3110, 1780, 1716, 1498, 1385, 1080, 820, 722 cm"1; NMR 7.10-7.70 (4 H, m, phenyl ), 2.30-2.60 (4 H, m, =CCH2), 1.10 (3 H, d, J = 7.0 Hz, CHCH3), 1.03, 0.98 ppm (3 H each, s, CCH3); mass spectrum m/e (rel intensity) 401, 403 (M+, 100, base peak, C2iH24N02Br), 386, 388 (6), 278, 280 (91), 265, 267 (9). Recrystallization from ethanol gave crystals for X-ray analysis.…”