Anthraquinones tetracyclic

Benzanthrone (6.73) is the source of various commercially important violet, blue and green vat dyes. This tetracyclic system can be prepared from a mixture of anthraquinone and propane-1,2,3-triol (glycerol) by heating with iron powder in concentrated sulphuric acid. The reaction involves reduction of anthraquinone to anthrone (6.74) followed by condensation (Scheme 6.14) with propenal (acrolein), the latter compound being generated... 

Most of the previously identified 25 chlorinated anthraquinones are found in lichen and fungi (1). The newly discovered examples have a wider range of sources. Studies of the lichen Nephroma laevigatum from the British Columbia coast have identified the new anthraquinone, 7-chloro-l-O-methyl-co-hydroxy-emodin (2157), and the two novel hypericins, 7,7 -dichlorohypericin (2158) and 2,2, 7,7 -tetrachlorohypericin (2159) (1931), as well as 5-chloroemodin (2160), 5-c h I oro -1 - (9 - m e t h v I - o >- h yd ro x ye m od i n (2161), and 5-chloro-co-hydroxyemodin (2162) (1932). In addition to containing several known chlorinated anthraquinones, the Scandinavian fungus Dermocybe sanguinea has afforded the new 5,7-dichloroendocrocin (2163) (1933). The novel tetracyclic anthraquinones... 

Intramolecular Marschalk reaction. Ai. intramolecular Marschalk reaction (9, 376) can be used to effect a synthesis of anthracvclinones from anthraquinones. Thus the oi-hydroxy aldehyde 2, formed on saponification of the a-hydroxydichloride 1, on reduction of the quinone group cyclizes in the alkaline medium to the tetracyclic tran.s- and ci/j-diols(3and4)inaboutequal amounts. Cyclization underphase-transfer conditions results in improved yields and, more importantly, can alter the stereoselectivity. Triton B is the most effective catalyst for stereoselective cyclization to the desired natural tran -diol. 

The anthracyclines are aminoglycosidic derivatives of tetracyclic compounds that contain an anthraquinone chromophore. Originally, dauno-mycin and adriamycin, its hydroxy analogue, were isolated from cultures of Streptomyces peucetiusd The main target of these drugs appears to be DNA, most likely by formation of an intercalation complex. The drugs also affect topoisomerase II, an enzyme which interacts with the DNA that has been modified by intercalation. ... 

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