Abstract by Prof. Dr. Reinhard Brückner, Albert Ludwig University of Freiburg

The First Stereoselective Total Synthesis of a Dimeric (Naphthoquinono) pyrano-?-lactone: (+) - ?-Actinorhodin

We accomplished the first total synthesis of an isomerically pure naphthoquinopyrano-?-lactone dimer - ?-actinorhodin - in 11 steps. It is the first stereoselective total synthesis of a naphthoquinonopyrano-?- lactone dimer at all. Others who tried the same, obtained dimers which were diastereomeric mixtures or no dimer at all. Two steps of our approach exploit pairs of peri -placed MeO groups as unusual selectivity controls. The respective MeO groups convey the steric bulk of a bromo or iodo substitute located ortho to a first MeO group as steric hindrance into the vicinity of another MeO group. This relay effect was indispensable for exerting (a) regiocontrol in an aromatic bromination and (b) diastereocontrol in an oxa-Pictet Spengler cyclization. The absolute configuration of our target was established by the asymmetric Sharpless dihydroxylation of a ?, ?-unsaturated ester. It provided the lactone moiety of a bromonaphthalene, which was poised to dimerize to the core of ?-actinorhodin by Suzuki couplings. The unsaturated ester stemmed from a Heck coupling of ethyl vinyl acetate with a bromoiodonaphthalene. The latter was synthesized from 1,5-dihydroxynaphthalenes via monoiodo-1,4,5,8-tetramethoxynaphthalenes.

Curriculum Vitae of Prof. Dr. Reinhard Brückner

Born May 5, 1955 in Braunschweig Schooling 1962-1974 in Darmstadt Chemistry studies 1974-1980 LMU Munich Dr. rer nat. 1984 with Prof. Dr. Rolf Huisgen Postdoctoral studies 1984-85 with Prof. Paul A. Wender at Stanford University Habilitation 1985-89 under the auspices of Prof. Dr. Reinhard Hoffmann at Philipps-Universität Marburg Professor of Organic Chemistry at Julius-Maximilians-Universität Würzburg 1991-1992 Professor of Organic Chemistry at Georg-August-Universität Göttingen 1992-1998 Professor of Organic Chemistry at Albert-Ludwigs-Universität Freiburg since 1998 Visiting Professorships : University of Wisconsin, Madison; Universidade de Santiago de Compostela, Spain; Indiana University, Bloomington; Stellenbosch University, South Africa ADUC award (1989) Awardee of the Karl Winnacker foundation (1990) Chemistry Award of the Academy of Science of Göttingen (1990) Society of Synthetic Organic Chemistry Japan Lectureship (1996) Literature Prize of the Foundation of the Chemical Industries (1998) Novartis Chemistry Lectureship (2008) 2000-2004 and Elected Reviewer of the Study Section "Organic Chemistry" of the 2004-2008 German Research Foundation (DFG) 2000-2004 and Elected Vice-President and President, respectively, of the 2004 -2008 "Division of Organic Chemistry" of the German Chemical Society (GDCh) Research interests: natural product synthesis and the development of pertinent methodology Teaching interests: author of a textbook both in German ("Reaction Mechanisms") and English ("Organic Mechanisms" ); co-author of a 2-volume laboratory course ("Practical preparative Organic Chemistry")