370. The chemistry of fungi. Part XXXII. Rosololactone, a metabolite of Trichothecium roseum Link

Abstract

Rosololactone, C,oH3003, from the mycelium of T . roseurn Link, is a diterpenoid y-lactone containing a secondary hydroxyl group and a vinyl residue and on dehydrogenation yields 1 : 7-dimethylphenanthrene. Dehydration of dihydrorosololactone readily gives a dienoic acid, dihydrorosenic acid, which on hydrogenation is converted into tetrahydrorosenic acid. Lactonisation of this acid yields a mixture of allo-and neo-hydroxyrosanoic y-lactone identical with the two y-lactones from iso(?)ros-11 : 12-en-16-oic acid (Part XXXI l ) , thereby establishing a close structural affinity between rosoloand rosenono-lactone.IN addition to the major constituent, rosenonolactone, the mycelium of Trichothecium Yoseum Link contains a minor metabolite which in Part VI was designated rosonolactone. The present communication details an investigation on the chemistry and structure of this compound which has the formula, C20H3003. Since the metabolite, which appears

New Trichothecenes Isolated from Holarrhena floribunda

“…Rosololactone (9): amorphous white solid (66 mg, 0.19% of extract); mp 185 °C, [R]D -3°(c 1.4, CH2Cl2) {lit 34. mp 186 °C [R]D +6.3°)}; UV and IR data identical to those reported in the literature;34 1 H NMR data, see Table 4; HREIMS m/z 318.21963 (calcd for C20H30O3, 318.21950).…”

The stereochemistry of the Grignard reaction of some boat ring ketones in the diterpenoids

“…The formation of the 7β-hydroxy-7αmethylrosenonolactone 2 parallels the stereochemistry of the reduction of rosenonolactone 1 by sodium borohydride which gives the 7β-alcohol. 7 Oxidation of the C-6 alcohol rosololactone 3 with chromium trioxide in sulfuric acid gave the known 5 Hence, the adduct has the 6β-hydroxyl-6α-methyl (equatorial methyl) configuration. The stereochemistry of this Grignard reaction again parallels that of the sodium borohydride reduction which regenerates 6β-hydroxyl of rosololactone.…”