10023-11-7Relevant academic research and scientific papers
3. Naphthopyranquinone Antibiotics: Novel Enantioselective Syntheses of Frenolicin B and Some of Its Stereoisomers
Masquelin, Thierry,Hengartner, Urs,Streith, Jacques
, p. 43 - 58 (1997)
Two new enantioselective syntheses of the naphthopyranquinone antibiotic frenolicin B (1), of its enantiomer 2, and of its diastereoisomers 3 and 4 were accomplished using two different routes from optically active β-hydroxy esters (R)- and (S)-11 and 18.
The divergent asymmetric synthesis of kalafungin, 5-epi-frenolicin B and related pyranonaphthoquinone antibiotics
Donner, Christopher D.
, p. 377 - 386 (2013/01/15)
A divergent, asymmetric method for the synthesis of pyranonaphthoquinones is reported. The synthetic strategy applies a Staunton-Weinreb annulation between substituted ortho-toluates and the (R)-pyran-2-one 7 to construct the key naphthopyranone intermediates. Stereoselective introduction of either a methyl or propyl C5 alkyl substituent by use of Grignard addition/silane- mediated reduction and a sequence of oxidations gave a series of pyranonaphthoquinones including kalafungin 1, 5-epi-9-methoxykalafungin 34 and 5-epi-frenolicin B 24.
