Directed aromatic functionalization in natural-product synthesis: Fredericamycin A, nothapodytine B, and topopyrones B and D

• Charles Dylan Turner and
• Marco A. Ciufolini

Beilstein J. Org. Chem. 2011, 7, 1475–1485, doi:10.3762/bjoc.7.171

• . Aqueous workup arguably converted 68 into a dihydroanthraquinone, which upon exposure to the atmosphere was rapidly oxidized to the desired anthraquinone 69. The yield of this material was a modest 17% after purification, the remaining balance of the initial mass of 65 being the debrominated material 70

• ) regardless of the length of time (from 3 to 12 h) over which the reaction mixture was allowed to evolve following the addition of t-BuLi to 66. As a control experiment, we examined the preparation of the simpler anthraquinone 72 by the same method (Scheme 14). This exercise established that 72 formed

• upon CD3OD quench). Accordingly, the organolithium species thus generated was processed as detailed earlier in Scheme 14, leading to a mixture of the desired anthraquinone 76, obtained in 20% yield after chromatography, along with desbromo product 75, again isolated in 60–70% yield (Scheme 16). The

Hyperbranched polyethylenimine bearing cyclodextrin moieties showing temperature and pH controlled dye release

• Indra Böhm,
• Susanne Katharina Kreth and
• Helmut Ritter

Beilstein J. Org. Chem. 2011, 7, 1130–1134, doi:10.3762/bjoc.7.130

• Indra Bohm Susanne Katharina Kreth Helmut Ritter Institut für Organische und Makromolekulare Chemie II, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany Fax: (+49) 211 8115840 10.3762/bjoc.7.130 Abstract The release of anthraquinone dyes from β-cyclodextrin

• : anthraquinone; cyclodextrin; drug delivery; polyethylenimine; release; Introduction The development of novel materials and their use as drug delivery systems has gained increased interest in the last few decades [1][2][3]. In this context, certain stimuli responsive behaviors are required [4][5]. Hence, the

• heating [25]. For optical visualization of the attachment and release of suitable molecules, two anthraquinone dyes were chosen as model compounds in the present work [26]. Results and Discussion 5,8-Dichloro-1,4-dihydroxyanthraquinone (1) and 1,4-bis-N-adamantylaminoanthraquinone (2) were used as model

Functionalization of anthracene: A selective route to brominated 1,4-anthraquinones

• Kiymet Berkil Akar,
• Osman Cakmak,
• Orhan Büyükgüngör and
• Ertan Sahin

Beilstein J. Org. Chem. 2011, 7, 1036–1045, doi:10.3762/bjoc.7.118

• constitute potentially important keys for the synthesis of pharmaceutical chemicals [4][5][6][7], natural products [8][9] and donor properties [10][11]. Anthraquinone 28 may be used as precursor for 9,10-disubstituted-2-phenoxy-anthracene-1,4-dione derivatives that are difficult to synthesize by other routes

• . There has been much interest in the preparation of phenoxy-1,4-anthraquinone derivatives due to their anti-trypanosomal activity. Bolognesi et al. designed and synthesized a small library of 2-phenoxy-1,4-anthraquinone derivatives, all of which showed inhibitory activity toward either Trypanosoma or