Synthesis, EPR, ENDOR and TRIPLE resonance investigations of anthracycline-related semiquinones
作者:Hartmut B. Stegmann、Thomas Jülich、Ulrike Höfler、Paul Schuler、Wolfhard Koch、Karsten Krohn、Astrid Eickhoff
DOI:10.1002/mrc.1260310510
日期:1993.5
substituted anthraquinones related to anthracyclines is described. One‐electron reduction of these compounds yields the corresponding semiquinones, which were characterized by EPR, ENDOR and TRIPLEresonancespectroscopy. The data indicate a rapid conformational interconversion of the cyclohexene moiety (ring A in the anthracyclines). The low‐temperature structures could be assigned to half‐chair conformers
Synthetic Anthracyclinones, XXXI. Total Synthesis of Racemic εe-Rhodomycinonesvia Keto-Ester Cyclization
作者:Karsten Krohn、Wahyudi Priyono
DOI:10.1002/jlac.198619860902
日期:1986.9.12
The ketoesters 15 – 17b were prepared by regioselective alkylation of the anthraquinone acetals 12 – 14 followed by cleavage of the acetals and methyl ethers and esterification. The tetracyclic trans-β-hydroxy esters 25 – 27b were formed predominantly upon treatment of 15 – 17b with Triton B in pyridine, whereas lithium amides in THF gave only the cis-hydroxy esters 28 and 29a. Stereoselective hydroxylation