Toward a New Test of the Relativistic Time Dilation Factor by Laser Spectroscopy of Fast Ions in a Storage Ring

Hyperfine Interactions - The frequency measurement of Doppler-shifted optical lines of ions circulating in a storage ring at high speed permits a sensitive test of the relativistic Doppler-formula...     

Synthese der citromycinone stereoselektive öffnung eines epoxids zum cis-diol

The citromycinone-derivatives $\text{14}$ and $\text{15}$ have been obtained by intramolecular Marschalk cyclisation of α-hydroxyaldehyde $\text{12}$. An unexpected opening of epoxide $\text{16}$ to $\text{cis}$-diol $\text{14}$ was observed. By exclusion of the alternative formula $\text{2}$ structure $\text{3}$ is proposed for α-citromycinone.     

Absolute configuration of 1β,10β-epoxydesacetoxymatricarin isolated from Carthamus oxycantha by means of TDDFT CD calculations

The absolute configuration of 1β,10β-epoxydesacetoxymatricarin 1, a sesquiterpenoid isolated from Carthamus oxycantha, was established by TDDFT CD calculations in combination with single crystal X-ray analysis. Since the solid-state CD spectrum shows contributions from intermolecular interactions in the crystal, 1 represents a test case for our solid-state CD/TDDFT approach.     

Eucleanal A and B:Two new napthalene derivatives from Euclea divinorum

Two new naphthalene derivatives named eucleanal A and B（1 and 2） were isolated from Euclea divinorum.The structures of the new compounds were elucidated by detailed spectroscopic analysis such as ¹H,¹³C NMR,COSY,HMQC,HMBC and HREIMS mass spectrometry.     

Biomimetic synthesis of the racemic angucyclinones of the aquayamycin and WP 3688-2 types

The first synthesis of the racemic 8-deoxy WP3688-2 angucycline antibiotic (3), with characteristic cis-hydroxy groups at C-4 a and C-12b, is reported. Key steps involve the coupling, mediated by samarium diiodide, of the bicyclic trione 37 to the tricyclic cis-diol 39. Biomimetic aldol cyclization of the corresponding dione 41 gave a mixture of the tetracyclic cis- and trans-3,4a-diols 42 and 43, which were oxidized by cerium ammonium nitrate to the quinones 45 and 3. The synthetic compounds 45 and 3 corresponded in configuration to the angucycline antibiotics aquayamicin (1) and WP 3688-2 (2), respectively.