Biomimetic Synthesis of Deca- and Dodecaketide-Derived Quinone Antibiotics

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

“…This method was used for the preparation of chromones, 1,2 coumarines, 3,4 and benzindenopyrandiones. 5 The scope in the choice of residue R on the ester is broad and it can be aliphatic, olefinic, aromatic, or heteroaromatic, as investigated by Kraus et al 6 The construction of b-diketo side chains on an aromatic or quinoide nucleus is ideally suited for the synthesis of aromatic polyketide derived natural products and was used in the biomimetic-type synthesis of anthracylines 7 and angucyclines 8 (review 9 ). Similarly, the Baker-Venkataraman reaction was employed in the synthesis of a large group of anthrapyran antibiotics.…”

Mechanism and Application of Baker–Venkataraman O→C Acyl Migration Reactions

“…105,110,112 Similarly, the synthesis of aromatic-polyketide-derived natural products and the biomimetic-type synthesis of anthracyclines 113 and angucyclines 114 includes the construction of β-diketo side chains on an aromatic or quinoid nucleus. 115 In efforts to produce such β-diketo products, Krohn et al attempted an enantioselective acyl-transfer reaction with α-oxygenated esters under Baker-Venkataraman conditions (Scheme 23). 111 In their efforts to achieve this, the base-catalyzed Baker-Venkataraman rearrangement of (S)-2-acetyl-1-hydroxyanthraquinone ester 105 proceeded, with virtually no racemization, to the β-diketo anthraquinone product (S)-106 (50%).…”

Bioactive C-Glycosides from Bacterial Secondary Metabolism

“…This route is unattractive, because it requires that a weakly nucleophilic naphthoquinone must undergo an intermolecular reaction with a ketone, under physiological conditions. Aldol-like reactions of this type are known in the synthetic literature, but they generally require Marschalk conditions [83,84] in which the quinone is temporarily reduced. Moreover, the intermolecular Marschalk reaction generally requires a more reactive aldehyde electrophile, and often alkaline conditions and elevated temperatures.…”