Regiodefined synthesis of brominated hydroxyanthraquinones related to proisocrinins

• Joyeeta Roy,
• Tanushree Mal,
• Supriti Jana and
• Dipakranjan Mal

Beilstein J. Org. Chem. 2016, 12, 531–536, doi:10.3762/bjoc.12.52

• ), isolated from the crinoid Holopus rangii, shows remarkable cytotoxic activities. Topopyrone B (2) stabilizes DNA topoisomerase I and DNA topoisomerase II. Haloemodin (3) acts as an antibacterial agent inhibiting DNA gyrase and bacterial topoisomerase I. 6-O-Methyl-7-chloroaveratin (4) displays potent

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

• ; nothapodytine; organolithium compounds; topopyrone; Review Our laboratory is primarily interested in the total synthesis of natural products, and does not conduct research on directed aromatic functionalization ("DAF") per se. On numerous occasions, however, DAF technology has been key to the success of

• lithiated 56 to 65, halogen–metal exchange, cyclization of aryllithium species 67) corresponds to an average of 55–60% yield per step. In such a light, the modest yield seemed quite acceptable, and indeed, with 69 in hand, the synthesis of topopyrone D was completed quickly. As shown in Scheme 15

• detailed in the isolation paper [90][91]. An unexpected problem materialized when the foregoing sequence was transposed to the case of topopyrone B, the synthesis of which required the execution of the same operations starting with benzamide 57. Surprisingly, this material resisted deprotonation under