- Regioselective lactonization of naphthoquinones: Synthesis and antitumoral activity of the WS-5995 antibiotics
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An acid promoted quinolactonization of naphthoquinones has been developed, providing direct access to either ortho or para isomers as desired. Application of this methodology in syntheses of the antibiotics WS- 5995A, WS-5995C and functional analogs is demonstrated. Preliminary antitumoral activity of the analogs is presented together with electrochemical analysis. (C) 2000 Elsevier Science Ltd.
- Qabaja, Ghassan,M. Perchellet, Elisabeth,Perchellet, Jean-Pierre,Jones, Graham B.
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p. 3007 - 3010
(2007/10/03)
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- Synthesis of antibiotics WS 5995 A and C and related compounds by palladium-catalyzed coupling of 2-bromonaphthoquinones with organostannanes
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The synthesis of arylnaphthoquinones can be performed simply by using as the key reaction the Pd(0)- and Cu(I)-catalyzed coupling of arylstannanes with 2-bromonaphthoquinones as the electrophiles. The palladium-catalyzed coupling reaction is general and allows for the functionalization of the unprotected quinone nucleus with alkyl, alkenyl, and aryl substituents. The coupling process tolerates the presence of a chelated peri hydroxyl and steric crowding of a 2,6-disubstituted arylstannane, although the preparation of a 2,6,2',6'-tetrasubstituted biaryl by coupling of 2-bromo-3,5-bis(acetyloxy)-1,4-naphthoquinone as the electrophile with 2,6-disubstituted arylstannanes was unsuccessful. The syntheses of quinonoid antibiotics WS 5995 A and C was accomplished by using this method as the key step. Benz[b]phenanthridinone 1, hypothetical intermediate in the biosynthesis of benz[b]phenanthridine alkaloids, was also prepared from antibiotic WS 5995 C or by addition of ammonia to the 2-aryl-1,4-naphthoquinone 41 followed by heterocyclization.
- Echavarren,Tamayo,Cardenas
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p. 6075 - 6083
(2007/10/02)
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- THE TOTAL SYNTHESIS OF THE ANTI-COCCIDIAL AGENTS WS-5995
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A total synthesis of the three anti-coccidial agents WS-5995 A, B, and C by a Diels-Alder route is described.An intramolecular lactonization involving the displacement of a chlorine atom on a napthoquinone was the key step in the synthesis of A.
- McKenzie, Thomas C.,Choi, Woo-Baeg
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p. 1523 - 1532
(2007/10/02)
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- 1,4-Naphtoquinone derivatives and their use in treating coccidiosis
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1,4-naphthoquinone derivatives represented by the following general formula: STR1 (wherein R1 represents a hydrogen atom, a hydroxy group, a lower alkoxy group or an arylthio group, R2 represents a carboxy group, an esterified carbox
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- STRUCTURE ELUCIDATION AND SYNTHESIS OF A NEW ANTICOCCIDICAL SUBSTANCE ISOLATED FROM STREPTOMYCES AURANTICOLOR
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The structure elucidation and synthesis of WS 5995, produced by Streptomyces auranticolor, were described.
- Tanaka, Hirokazu,Itoh, Yoshikuni,Ikushima, Hiroichi,Okamoto, Masanori,Kawai, Yoshio,Imanaka, Hiroshi
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p. 4359 - 4360
(2007/10/02)
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