M. Thiel
Schering AG
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Featured researches published by M. Thiel.
Tetrahedron Letters | 1996
Hermann Künzer; M. Thiel; B. Peschke
Abstract Acceptor substituted 3-methoxyestra-1,3,5(10),6-tetraene derivatives 3 , 4 and 5 have been prepared and exploited in a synthesis of the title compounds 13 and 15 by key Michael-type addition reactions involving dimethylsulfoxonium methylide. α-Cyclopropanation was only slightly favored on the sulfone analogue 3 but strongly so on the (R)-sulfoxide 4 . On the contrary, the (S)-sulfoxide 5 displayed a weak preference for β-face attack.
Tetrahedron Letters | 1988
Hermann Künzer; M. Thiel
Abstract Nucleophilic attack by the lithium anion of acetonitrile on the diastereomeric chromium tricarbonyl complexes of 17β-(tert-butyldimethylsilyloxy)-3-methoxyestra-1,3,5(10)-triene leads to the corresponding 3-cyanomethyl complexes, useful intermediates en route to 3-alkylated estra- 1,3,5(10)-trienes.
Tetrahedron Letters | 1988
Hermann Künzer; M. Thiel
Abstract The nucleophilic addition - oxidation reaction between the lithium anion of 1,3-dithiane and a mixture of complexes 3 and 4 installs the heterocycle predominantly at C-1 of the steroid to afford 5. This intermediate is converted into C-1 substituted steroids 6–12.
Tetrahedron Letters | 1994
Hermann Künzer; M. Thiel; Gerhard Sauer; Rudolf Wiechert
Abstract 17β-Acetyloxy-3-methoxy-6-(phenylsulfonyl)estra- 1,3,5(10),6-tetraene ( 4 ) was prepared as a substrate for conjugate addition of organolithium reagents by a three-step sequence starting from 17β-acetyloxy-3-methoxyestra- 1,3,5(10)-trien-6-one ( 2 ). While methyllithium showed only poor face selectivity, higher alkyllithium species (n-BuLi, t-BuLi) preferred to add to the β-face of 4 . 7α-Substituted derivatives, on the other hand, were generated stereoselectively by utilizing alkynyllithium reagents in the addition step. Removal of the phenylsulfonyl group at C(6) from alkylated products was achieved by conventional reductive desulfonylation methods. A short synthesis of the estrogen receptor antagonist 1 exploiting these observations is presented.
Tetrahedron Letters | 1994
Hermann Künzer; M. Thiel
Abstract A five-step reaction sequence including hydroxyl group-assisted cyclopropanation, C(17)-oxidation, B-ring aromatization, C(17)-reduction, and methyl ether cleavage has been devised to convert 2 into 12 . The synthesis of 19 took advantage of a facile isomerization of vinyl(benzyl)cyclopropane derivatives 6–11 into the corresponding β-bridged analogues 13–18 over molecular sieves.
Tetrahedron Letters | 1995
Hermann Künzer; M. Thiel
Abstract A four-step reaction sequence including (1) hydroxyl group-assisted epoxidation, (2) Jones oxidation, (3) DIBAH-reduction, and (4) epoxide deoxygenation has been devised in order to effect epimerization of 4 to 1 , the overall yield approaching 65%.
Tetrahedron Letters | 1996
G. Bojack; Hermann Künzer; K. Rölfing; M. Thiel
Abstract A four-step reaction protocol, culminating in an oxy-Cope rearrangement, has been developed to transform 2 into 7 . 9α-Alkylated derivatives of equilin, e.g., 12 , as well as C(7)-C(9) propano-bridged 19-norsteroids, like 17 , demonstrate synthetic potential for 7 in estrogen receptor ligand synthesis.
Tetrahedron Letters | 1995
T. Ruhland; M. Thiel; Hermann Künzer
Summary A stereoselective entry into a new class of pentacyclic estrogens is illustrated for the parent cycloprop[8,14]-8α-estra-1,3,5(10)-triene-3,17β-diol (3). Moreover, a high degree of regiocontrol in acidpromoted cyclopropane ring opening, 11→15 , offers an attractive, unprecedented access to 8-methyl 19-nor-8α-steroids.
Tetrahedron Letters | 1994
Hermann Künzer; M. Thiel; Gerhard Sauer
Abstract Oxidation of 3,17β-diacetyloxy-14,17α-ethanoestra-1,3,5(10)-triene (2) by ceric ammonium nitrate furnished the equilenin derivative 3. This intermediate was subsequently converted into epimeric C(11)-alcohols 7 and 9, the C(11)-methylene derivative 11, and olefin 13.
Synlett | 2000
K. Rölfing; M. Thiel; Hermann Künzer