4H-Anthra[1,2-b]pyran antibiotics. Total synthesis of the methyl ether of kidamycinone

The Antibiotics of the Pluramycin Group (4 H-Anthra [1,2-b] pyran Antibiotics)

“…Only one synthetic effort towards a pluramycinone derivative (viz. kidamycinone methyl ether (56» has come to our attention (36,37). HAUSER and coworkers used a sequence of progressive, regioselective annelation reactions.…”

First enantiospecific Baker–Venkataraman-rearrangements aiming at the total synthesis of chiral anthrapyran antibiotics

“…Similarly, the Baker-Venkataraman reaction was employed in the synthesis of a large group of anthrapyran antibiotics. [10][11][12] In this connection it was of interest that in contrast to normal phenolic esters 13 the intermolecular C-acylation was not possible with acylated anthraquinone precursors (only O-acylation was observed 14 ), whereas the intramolecular version gave good results in the C-C coupling products and was the only option for the ketide C-C chain elongation with quinoide substrates. 12 However, to the best of our knowledge, no 0957 examples of enantioselective acyl transfer reactions with homochiral or a-oxygenated esters B under Baker-Venkataraman conditions are known.…”

The synthesis and biological activity of novel anthracenone-pyranones and anthracenone-furans

“…These key reactions include; the BakerVenkataraman rearrangement with cyclisation, 9,10 a 6-endo-dig cyclisation of alkyne ketones, [11][12][13][14][15] a Friedel-Crafts acylation 16 and cyclisation of b-diketones 17,18 among others. 19,20 In 2013, we described a racemic synthesis of anthrapyranones through the annulation of a b-keto-sulfoxide and an aldehyde. 21 Interestingly, a recent report on a non-metal mediated synthetic ring forming processes on simple chromones has come to light 22 along with the oxidative alkylation of these ring systems.…”