From the ethno-medicinally used leaves of Mallotus oppositifolius, four acylphloroglucinol derivatives, namely Acronyculatin SU (1-3) and Mallotojaponin D (4) were isolated along with seven known compounds (5-11). Structures were elucidated by comprehensive spectroscopic analyses and HRMS data. Absolute configurations were assigned by careful comparison of their specific optical rotation with those of closely related compounds.
View Article and Find Full Text PDFIn the course of the development of a new and reliable analytical method for the PCT, a group of environmental contaminants, six coplanar terphenyl congeners were synthesized and characterized by means of spectroscopic methods. These congeners are 3,3″,4,4″,5-pentachloro-p-terphenyl, 3,3″,4,5,5″-pentachloro-p-terphenyl, 3,3″,4,5″-tetrachloro-m-terphenyl, 3,3″,4,4″,5-pentachloro-m-terphenyl, 3,3″,5,5',5″-pentachloro-m-terphenyl, and 3,3″,4,4″,5,5″-hexachloro-m-terphenyl. A combination of silica gel column chromatography and preparative NP-HPLC was successfully applied for the first time for the isolation of especially the asymmetrically chlorinated target compounds from product mixtures of the syntheses.
View Article and Find Full Text PDFFeeding of (2,3,4,5,6-(13) C5 )mevalonolactone to the fungus Hypomyces odoratus resulted in a completely labeled sesquiterpene ether. The connectivity of the carbon atoms was easily deduced from a (13) C,(13) C COSY spectrum, revealing a structure that was different from the previously reported structure of hypodoratoxide, even though the reported (13) C NMR data matched. A structural revision of hypodoratoxide is thus presented.
View Article and Find Full Text PDFThe genuine major benzylisoquinoline alkaloid occurring in the traditional medicinal plant greater celandine (Chelidonium majus L.) is 13,14-dihydrocoptisine and not - as described previously - coptisine. Structure of 13,14-dihydrocoptisine was elucidated.
View Article and Find Full Text PDFThe [2.2]paracyclophane moiety is used as a spacer to connect the ends of a hex-3-ene-1,5-diyne unit, a π-system that on thermolysis usually cycloaromatizes to a benzene ring (Bergman cyclization). For the preparation of the pseudo-geminally-bridged system 9, the diacetylene 3 was chain-extended to the diol 16, which after conversion to the pseudo-geminal dibromide 17 was ring-closed by treatment with LiHMDS/HMPA to the [2.
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