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Publications - Bioorganic Chemistry

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Publications

Wender, P. A.; Wessjohann, L. A.; Peschke, B.; Rawlins, D. B.; The pinene path to taxol: Readily accessible a-ring building blocks based on novel alkyl- and alkenyllithium reagents with internal carbonyl groups Tetrahedron Lett. 36, 7181-7184, (1995) DOI: 10.1016/0040-4039(95)01491-Y

The synthesis and chemistry of the novel reagents and stereochemically defined taxane A-ring building blocks 7e–9e are described, providing the basis for the solution to problems previously encountered in the development of syntheses of taxol and its analogs based on pinene.
Publications

Morel, A. F.; Machado, E. C.; Wessjohann, L. A.; Cyclopeptide alkaloids of Discaria febrifuga (Rhamnaceae) Phytochemistry 39, 431-434, (1995) DOI: 10.1016/0031-9422(94)00924-I

From the methanol extract of the root bark of Discaria febrifuga Mart., in addition to the already described alkaloid, a new peptide alkaloid discarine-L has been isolated and its structure elucidated. This alkaloid differs from most of the known 14-membered peptide alkaloids by a 2-hydroxy-2-phenethylamine residue.
Publications

Kramell, R.; Atzorn, R.; Schneider, G.; Miersch, O.; Brückner, C.; Schmidt, J.; Sembdner, G.; Parthier, B.; Occurrence and identification of jasmonic acid and its amino acid conjugates induced by osmotic stress in barley leaf tissue J. Plant Growth Regul. 14, 29-36, (1995) DOI: 10.1007/BF00212643

The effect of osmotically active substances on the alteration of endogenous jasmonates was studied in barley (Hordeum vulgare L. cv. Salome) leaf tissue. Leaf segments were subjected to solutions of d-sorbitol, d-mannitol, polyethylene glycol 6000, sodium chloride, or water as a control. Alterations of endogenous jasmonates were monitored qualitatively and quantitatively using immunoassays. The structures of jasmonates isolated were determined on the basis of authentic substances by capillary gas chromatography-mass spectrometry. The stereochemistry of the conjugates was confirmed by high performance liquid chromatography with diastereoisomeric references. In barley leaves, jasmonic acid and its amino acid conjugates, for example, with valine, leucine, and isoleucine, are naturally occurring jasmonates. In untreated leaf segments, only low levels of these native jasmonates were found. After treatment of the leaf tissues with sorbitol, mannitol, as well as with polyethylene glycol, an increase of both jasmonic acid and its conjugates could be observed, depending on the stress conditions used. In contrast, salt stress was without any stimulating effect on the levels of endogenous jasmonates. From barley leaf segments exposed to sorbitol (1m) for 24 h, jasmonic acid was identified as the major accumulating compound. Jasmonic acid-amino acid conjugates increased likewise upon stress treatment.
Publications

Braga, A. L.; Silveira, C. C.; Dornelles, L.; Zeni, G.; Galarza, F. A. D.; Wessjohann, L. A.; Catalyst-Dependent Selective Synthesis of O/S- and S/S-Acetals from Enol Ethers Synth. Commun. 25, 3155-3162, (1995) DOI: 10.1080/00397919508015466

Enol ethers are reacted with mercaptanes to give the corresponding O/S- or S/S-acetals in medium to high yield. Either product can be formed selectively depending on the acid catalyst and the reaction time applied.
Books and chapters

Wender, P. A.; Badham, N. F.; Conway, S. P.; Floreancig, P. E.; Glass, T. E.; Houze, J. B.; Krauss, N. E.; Lee, D.; Marquess, D. G.; McGrane, P. L.; Meng, W.; Mucciaro, T. P.; Mühlebach, M.; Natchus, M. G.; Ohkuma, T.; Peschke, B.; Rawlins, D. B.; Shuker, A. J.; Sutton, J. C.; Taylor, R. E.; Tomooka, K.; Wessjohann, L. A.; The Pinene Path to Taxanes ACS Sym. Ser. 583, 326-339, (1995) ISBN: 9780841215078 DOI: 10.1021/bk-1995-0583.ch024

Taxol is a recent and striking example of the continuing impact of natural products chemistry on science and human health and a reminder of the significant return that is realized through investment in basic research. First isolated in the sixties from the bark of the Pacific Yew by chemists Wall, Wani, and their colleagues working in collaboration with the National Cancer Institute (1), taxol was found to possess a novel polycyclic structure (1) punctuated by a central eight-membered ring. Interest in the chemotherapeutic potential of this compound was stimulated by early cytotoxicity studies and greatly amplified by the subsequent proposal by Horwitz and coworkers that taxol operates through a new molecular mode of action involving the facilitated assembly and stabilization of microtubules (2). Clinical trials of taxol in the eighties proved to be sufficiently promising to warrant its subsequent approval for use in the treatment of ovarian cancer and, more
Books and chapters

Adam, G.; Porzel, A.; Schmidt, J.; Schneider, B.; Voigt, B.; New Developments in Brassinosteroid Research Stud. Nat. Prod. Chem. 18, 495-549, (1995) DOI: 10.1016/S1572-5995(96)80033-0

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