An EXAFS, and preliminary X-ray crystallographic, investigation of an iron-containing product from the lichen Cladonia deformis.

An iron-containing product in the acetone extract from the lichen Cladonia deformis has been investigated using chemical, spectroscopic and X-ray crystallographic methods. Visible-near UV, EPR and IR spectra indicate that the iron is present as high-spin Fe(III) and coordinates in an oxygen-containing environment arising from graciliformin (or graciliformin-like) ligands. This has been confirmed by an XAS (X-ray absorption) study using synchrotron radiation. Comparison of the EXAFS and XANES results with those obtained from a model, tris(pent-2,4-dionato)Fe(III), and detailed fitting using the single-scattering, curved-wave formalism for the EXAFS strongly supports the presence of a Fe(III) coordinated to five oxygen atoms from the graciliformin.

Bacterial carotenoids. XLVIII. Total syntheses of carotenes of the 1,2-dihydro series.

The total syntheses of 1,2,7,8,1',2',7',8'-octahydro-psi,psi-carotene (1), 1,2,7,8-tetrahydro-psi,psi-carotene (2), 1,2,1',2'-tetradehydro-psi,psi-carotene (3), 1,2-dihydro-psi,psi-carotene (4), 1,2-dihydor-3,4-didehydro-psi,psi-carotene (5), and 1,2,1',2'-tetrahydro-3,4,3',4'-tetrahydro-psi,psi-carotene (6) are described. The properties of products and intermediates, including the three new apocarotenals 1,2,7,8-tetrahydro-12'-apo-psi-caroten-12'-al (20), 1,2-dihydro-8'-apo-pse-caroten-8'-al (25), and 1,2-dihydro-3,4-didehydro-8'-apo-psi-carotene-8'-al (32), are reported. A fragment ion at M68 on electron impact appears to be characteristic for carotenoids with a 1,2,7,8-tetrahydro end-group.