The methanolic extract of the whole plant of Echium glomeratum Poir. (Boraginaceae) has afforded five pyrrolizidine alkaloids, three that were (7S, 8R)-petranine (1), (7S, 8S)-petranine (2), and (7R, 8R)-petranine (3a) or (7R, 8S)-petranine (3b), comprising a tricyclic pyrrolizidine alkaloids subclass; and two that were known but to the species: 7-angeloylretronecine (4) and 9-angeloylretroneci...

The first polyhydroxylated pyrrolizidine alkaloid with a hydroxymethyl group at C-3 was isolated from pods of Alexa leiopetala (Leguminosae) and designated alexine 1. The Australian legume Castanospermum australe is also known to produce the same structural type of pyrrolizidines. There are reports of the isolation of australine (7a-epi-alexine) 2, 1-epi-australine 3, 3-epi-australine 4, and 7-...

The title compound, C(15)H(16)O(5)·H(2)O, is an inter-mediate of the Hooker oxidation reaction, used for the synthesis of 2-hydr-oxy-3-(2-methyl-prop-1-en-yl)naphthalene-1,4-dione (nor-lapachol). The packing in the crystal structure is arranged by an O-H⋯O hydrogen-bonded network along the [100] and [010] directions. Each organic mol-ecule is linked to four other mol-ecules via the hydr-oxy gro...

The title compound, C(23)H(22)N(2), was obtained using the three-component imino Diels-Alder reaction via a one-pot condensation between anilines, α-pyridine-carboxy-aldehyde and indene using BF(3)·OEt(2) as the catalyst. The mol-ecular structure reveals the cis-form as the unique diastereoisomer. The crystal structure comprises one-dimensional zigzag ribbons connected via N-H⋯N hydrogen bonds....

The pyrrolizidine alkaloids previously identified in floral honey attributed to Echium vulgare (Boraginaceae) have been detected (8000-14 000 ppm) in pure pollen collected from the anthers of Echium vulgare. Pyrrolizidine alkaloids and/or their N-oxides were isolated from the aqueous acid extracts of pollen by use of strong cation-exchange, solid-phase extraction and identified by liquid chroma...

In the title mol-ecule, C25H14O4, the fused-ring system consisting of four rings is approximately planar, with a dihedral angle of 9.62 (5)° between the planes of the indene ring system and the benzene ring. The di-hydro-indene-1,3-dione unit makes a dihedral angle of 63.50 (2)° with the mean plane of the fused-ring system. A weak C-H⋯O inter-action organizes the mol-ecules into a helical chain...

First attempts are described to prepare a precursor for an all-carbon analog of indigo, the tetracyclic triene 4. Starting from indan-2-one (9) the α-methylene ketone 13 was prepared. Upon subjecting this compound to a McMurry coupling reaction, it dimerized to the bis-indene derivative 17, rather than providing the tetramethyl derivative of 4, the hydrocarbon 14. In a second approach, indan-1-...

The synthesis of dibenzyl-(1S*,2S*)-2,3-dihydro-1H-indene-1,2-dicarboxylate has been realized through a diastereospecific bis-alkoxycarbonylation reaction, which starts from the cheap and easily available 1H-indene, benzyl alcohol, carbon monoxide. catalyst is formed in situ by mixing Pd(TFA)2, ligand N2,N3-bis(2,6-dimethylphenyl)butane-2,3-diimine, p-benzoquinone used as an oxidant, alcohol ac...