Phyllostictines A-D, oxazatricycloalkenones produced by Phyllosticta cirsii, a potential mycoherbicide for Cirsium arvense biocontrol

Phyllosticta cirsii, a fungal pathogen isolated from Cirsium arvense and proposed as biocontrol agent of this noxious perennial weed, produces in liquid cultures different phytotoxic metabolites with potential herbicidal activity. Four new oxazatricycloalkenones, named phyllostictines A-D, were isolated and characterized using essentially spectroscopic and chemical methods. Tested by leaf-puncture assay on the fungal host plant phyllostictine A proved to be highly toxic. The phytotoxicity decreases when both the dimension and the conformational freedom of the macrocyclic ring change, as in phyllostictines B and D, and it is totally lost when also the functionalization of the same ring is modified, as in phyllostictine C. Beside its phytotoxic properties, phyllostictine A has no antifungal activity, an interesting antibiotic activity only against Gram+ bacteria, and a noticeable zootoxic activity when tested at high concentrations. The integrity of the oxazatricycloalkenone system appears to be an important feature to preserve these activities.     

Trichiol and 3-epitrichiol acetate, novel cytotoxic sterols with an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system from the myxomycete Trichia favoginea var. persimilis

Trichiol (1) and 3-epitrichiol acetate (2), two new sterols, have been isolated from field-collected fruit bodies of the myxomycete, Trichia favoginea var. persimilis, and their structures elucidated by spectral data. Trichiol (1) and 3-epitrichiol acetate (2) possess an unprecedented 2,6-dioxabicyclo[2.2.2]octan-3-one ring system. Trichiol (1) was cytotoxic against HeLa cells, while compound 2 proved to exhibit reversal effect against TNF-related apoptosis inducing ligand (TRAIL)-resistant Jurkat cell lines.     

A new synthesis, including asymmetric synthesis, of spiro[4.n]alkenones from three components: cyclic ketones, chloromethyl p-tolyl sulfoxide, and acetonitrile; and a formal total synthesis of racemic acorone

1-Chlorovinyl p-tolyl sulfoxides were synthesized from several kinds of cyclic ketones and chloromethyl p-tolyl sulfoxide in good yields. Treatment of the 1-chlorovinyl p-tolyl sulfoxides with cyanomethyllithium at −78°C to room temperature gave spirocyclic enaminonitriles in high yields. Acidic treatment of the enaminonitriles afforded spiro[4.n]alkenones in good yields. By using an unsymmetrical cyclic ketone, α-tetralone, and optically active chloromethyl p-tolyl sulfoxide, this procedure afforded enantiomerically pure spiro[4.5]decenone in good yield with excellent asymmetric induction from the sulfoxide chiral center. By using this method a formal total synthesis of a racemic spirocyclic sesquiterpene, acorone, was realized.