We describe iron-catalyzed intermolecular oxidative coupling reactions of diarylamines to form substituted 2,2'-bis(arylamino)biaryl compounds, tetraarylhydrazines, and 5,6-dihydrobenzo[c]cinnolines with the same hexadecafluorinated iron-phthalocyanine catalyst. The mild formation of C-C or N-N bonds was controlled by the use of acidic or basic additives. In contrast to most iron-catalyzed dehydrogenative coupling reactions, ambient air could be used as the sole oxidant. Moreover, iron(III) chloride hexahydrate promoted a one-pot coupling and subsequent intramolecular dearomative coupling to give 10H-spiro[acridine-9,1'-cyclohexa-2',5'-dien-4'-ones].

In response to pheromone(s), Caenorhabditis elegans interrupts its reproductive life cycle and enters diapause as a stress-resistant dauer larva. This decision is governed by a complex system of neuronal and hormonal regulation. All the signals converge onto the nuclear hormone receptor DAF-12. A sterol-derived hormone, dafachronic acid (DA), supports reproductive development by binding to DAF-12 and inhibiting its dauer-promoting activity. Here, we identify a methyltransferase, STRM-1, that modulates DA levels and thus dauer formation. By modifying the substrates that are used for the synthesis of DA, STRM-1 can reduce the amount of hormone produced. Loss of STRM-1 function leads to elevated levels of DA and inefficient dauer formation. Sterol methylation was not previously recognized as a mechanism for regulating hormone activity. Moreover, the C-4 sterol nucleus methylation catalyzed by STRM-1 is unique to nematodes and thus could be a target for therapeutic strategies against parasitic nematode infections.

The spectroscopic characterization of corannulene (C(20)H(10)) is carried out by several techniques. The high purity of the material synthesized for this study was confirmed by gas chromatography-mass spectrometry (GC-MS). During a high-performance liquid chromatography (HPLC) process, the absorption spectrum of corannulene in the ultraviolet (UV) and visible (vis) ranges is obtained. The infrared (IR) absorption spectrum is measured in CsI pellets, and the Raman scattering spectrum is recorded for pure crystal grains. In addition to room temperature measurements, absorption spectroscopy in an argon matrix at 12 K is also performed in the IR and UV/Vis ranges. The experimental spectra are compared with theoretical Raman and IR spectra and with calculated electronic transitions. All calculations are based on the density functional theory (DFT), either normal or time-dependent (TDDFT). Our results are discussed in view of their possible application in the search for corannulene in the interstellar medium.

We describe the stereoselective transformation of diosgenin (4a) to (25R)-Delta(4)-dafachronic acid (1a),(25R)-Delta(7)-dafachronic acid (2a), and (25R)-cholestenoic acid (3a), which represent potential ligands forthe hormonal receptor DAF-12 in Caenorhabditis elegans. Key-steps of our synthetic approach are amodified Clemmensen reduction of diosgenin (4a) and a double bond shift from the 5,6- to the 7,8-position. In the 25R-series, the Delta(7)-dafachronic acid 2a exhibits the highest hormonal activity.

We report on the absorption spectra of the polycyclic aromatic hydrocarbon (PAH) molecules anthracene, phenanthrene, and pyrene carrying either an ethynyl (−C 2 H) or a butadiynyl (−C 4 H) group. Measurements were carried out in the mid infrared at room temperature on grains embedded in CsI pellets and in the near ultraviolet at cryogenic temperature on molecules isolated in Ne matrices. The infrared measurements show that interstellar populations of polyynyl-substituted PAHs would give rise to collective features in the same way non-substituted PAHs give rise to the aromatic infrared bands. The main features characteristic of the substituted molecules correspond to the acetylenic CH stretching mode near 3.05 µm and to the almost isoenergetic acetylenic CCH in-and out-of-plane bending modes near 15.9 µm. Sub-populations defined by the length of the polyynyl side group cause collective features which correspond to the various acetylenic CC stretching modes. The ultraviolet spectra reveal that the addition of an ethynyl group to a non-substituted PAH molecule results in all its electronic transitions being redshifted. Due to fast internal energy conversion, the bands at shorter wavelengths are significantly broadened. Those at longer wavelengths are only barely affected in this respect. As a consequence, their relative peak absorption increases. The substitution with the longer butadiynyl chain causes the same effects with a larger magnitude, resulting in the spectra to show a prominent if not dominating π-π * transition at long wavelength. After discussing the relevance of polyynyl-substituted PAHs to astrophysics, we conclude that this class of highly conjugated, unsaturated molecules are valid candidates for the carriers of the diffuse interstellar bands.

We describe iron-catalyzed intermolecular oxidative coupling reactions of diarylamines to form substituted 2,2'bis(arylamino)biaryl compounds, tetraarylhydrazines, and 5,6dihydrobenzo[c]cinnolines with the same hexadecafluorinated iron-phthalocyanine catalyst. The mild formation of CÀC or N À N bonds was controlled by the use of acidic or basic additives. In contrast to most iron-catalyzed dehydrogenative coupling reactions, ambient air could be used as the sole oxidant. Moreover, iron(III) chloride hexahydrate promoted a one-pot coupling and subsequent intramolecular dearomative coupling to give 10H-spiro[acridine-9,1'-cyclohexa-2',5'dien-4'-ones].

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