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Modified Mosher Method (modified + mosher_method)
Selected AbstractsTrichocladinols A,C, Cytotoxic Metabolites from a Cordyceps -Colonizing Ascomycete Trichocladium opacumEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 32 2009Huijuan Guo Abstract Trichocladinols A,C (1,3), three new metabolites, and the known massarigenin A (4), have been isolated from cultures of a Cordyceps -colonizing ascomycete Trichocladium opacum. Their structures were elucidated by NMR spectroscopy and X-ray crystallography. The absolute configuration of 1 was assigned by using the modified Mosher method and that of 3 was determined by X-ray crystallographic analysis of its (S)-MTPA ester. Compounds 1,3 showed modest cytotoxic effects against the human tumor cell lines HeLa and MCF-7. Structurally, compounds 1 and 2 possess a previously undescribed 2,9-dioxatricyclo[5.2.1.03,8]dec-4-ene skeleton.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Diarylheptanoids from the Rhizomes of Alpinia officinarumHELVETICA CHIMICA ACTA, Issue 1 2008Yi Sun Abstract A novel dimeric diarylheptanoid, (5R,5,R)-7,7,-(6,6,-dihydroxy-5,5,-dimethoxy[1,1,-biphenyl]-3,3,-diyl)bis[5-methoxy-1-phenylheptan-3-one] (1), and two new diarylheptanoids, (4E,6R)-6-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1-phenylhept-4-en-3-one (2) and (4E,6R)-6-hydroxy-1,7-diphenylhept-4-en-3-one (3), together with seven known diarylheptanoids, were isolated from the rhizomes of Alpinia officinarum. Their structures were elucidated by application of extensive spectroscopic analyses and the modified Mosher method. [source] Two Novel 14-Nor-13,14-secopodocarpanes from the Bark of Taiwania cryptomeriodesHELVETICA CHIMICA ACTA, Issue 2 2004Shih-Chang Chien The two novel compounds cryptomelactones A (3) and B (4) were isolated from the bark of Taiwania cryptomeriodes, besides the two known podocarpane derivatives 1,,13,14-trihydroxypodocarpa-8,11,13-trien-7-one (1) and 3,,13,14-trihydroxypodocarpa-8,11,13-trien-7-one (2), and were characterized by spectroscopic means including 2D-NMR techniques. Compounds 3 and 4 are novel-14-nor-13,14-seco-podocarpanes. The absolute configurations of 3 and 4 were determined by the modified Mosher method. The biotransformation mechanism of 3 and 4 is proposed. [source] Biosynthesis of the Myxobacterial Antibiotic Corallopyronin ACHEMBIOCHEM, Issue 9 2010Özlem Erol Abstract Corallopyronin A is a myxobacterial compound with potent antibacterial activity. Feeding experiments with labelled precursors resulted in the deduction of all biosynthetic building blocks for corallopyronin A and revealed an unusual feature of this metabolite: its biosynthesis from two chains, one solely PKS-derived and the other NRPS/PKS-derived. The starter molecule is believed to be carbonic acid or its monomethyl ester. The putative corallopyronin A biosynthetic gene cluster is a trans-AT-type mixed PKS/NRPS gene cluster, containing a ,-branching cassette. Striking features of this gene cluster are a NRPS-like adenylation domain that is part of a PKS-type module and is believed to be responsible for glycine incorporation, as well as split modules with individual domains occurring on different genes. It is suggested that CorB is a trans-acting ketosynthase and it is proposed that it catalyses the Claisen condensation responsible for the interconnection of the two chains. Additionally, the stereochemistry of corallopyronin A was deduced by a combination of a modified Mosher's method and ozonolysis with subsequent chiral GC analyses. [source] | ||||||||||