INTRODUCTION A previous investigation of pyrrolizidine alkaloids produced by nine species of Cryptantha identified at least two chemotypes within the genus. Other research has postulated that pyrrolizidine-N-oxide concentrations increase as the growing conditions become harsher, particularly with respect to water availability. Cryptantha crassipes is an endangered plant with a very limited dist...

In the title compound, C(17)H(11)F(3)O(2), the dihydro-indene ring is approximately planar with a maximum deviation of 0.024 (2) Å and makes a dihedral angle of 3.17 (8) Å with the adjacent benzene ring. In the crystal, mol-ecules are inter-connected by C-H⋯O inter-actions, forming an infinite chain along the c axis.

Excluding four H atoms, the molecule of the title compound, C(16)H(14)O, is almost planar, with an r.m.s. deviation of 0.0801 (2) Å. Due to p-π conjugation, the lengths of the two single bonds attached to the O atom are significantly different.

A novel and efficient route for rapid access to indeno[1,2-c]azepin-3(2H)-ones is described, which proceeds through a palladium-catalyzed tandem reaction of 2-alkynylhalobenzene with 2-alkynylbenzamide in the presence of PPh(3) or PCy(3). The indeno[1,2-c]azepin-3(2H)-ones which incorporate both indene and unsaturated seven-membered ring lactam skeletons are obtained in good to excellent yields.

New examples of ansa-titanocenes derived from 1,2-bis(2-indenyl)ethane have been prepared. The titanium-mediated reductive coupling of 2-(hydroxymethyl)indenes provided a convenient method for substrate dimerization. Alkyl substitution of the indene ring at C(3) improved the regioselectivity of the reductive coupling to provide the ethylene bis(2-indenyl)ansa-ligands in 29–62% yield.

Several insect lineages have developed diverse strategies to sequester toxic pyrrolizidine alkaloids from food-plants for their own defense. Here, we show that in two highly divergent insect taxa, the hemimetabolous grasshoppers and the holometabolous butterflies, an almost identical strategy evolved independently for safe accumulation of pyrrolizidine alkaloids. This strategy involves a pyrrol...

Rhodococcus sp. I24 can oxygenate indene via at least three independent enzyme activities: (i) a naphthalene inducible monooxygenase (ii) a naphthalene inducible dioxygenase, and (iii) a toluene inducible dioxygenase (TID). Pulsed field gel analysis revealed that the I24 strain harbors two megaplasmids of ∼340 and ∼50 kb. Rhodococcus sp. KY1, a derivative of the I24 strain, lacks the ∼340 kb el...

Polycyclic aromatic hydrocarbons (PAHs) are regarded as key intermediates in the molecular growth process that forms soot from incomplete fossil fuel combustion. Although heavily researched, the reaction mechanisms for PAH formation have only been investigated through bulk experiments; therefore, current models remain conjectural. We report the first observation of a directed synthesis of a PAH...