76191-50-9Relevant articles and documents
Annulation strategies for benzo[b]fluorene synthesis: efficient routes to the kinafluorenone and WS-5995 antibiotics.
Qabaja,Jones
, p. 7187 - 7194 (2007/10/03)
Intramolecular palladium-mediated arylation approaches to benzo[b]fluorenes have been investigated. The methodology has been applied in a short synthesis of tri-O-methylkinafluorenone, providing an effective alternative to Friedel-Crafts-based approaches. During the course of this work, an acid-promoted quinolactonization of naphthoquinones was also 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 analogues was demonstrated, and antitumoral activity of this class was determined.
Synthesis of antibiotics WS 5995 A and C and related compounds by palladium-catalyzed coupling of 2-bromonaphthoquinones with organostannanes
Echavarren,Tamayo,Cardenas
, p. 6075 - 6083 (2007/10/02)
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.
THE TOTAL SYNTHESIS OF THE ANTI-COCCIDIAL AGENTS WS-5995
McKenzie, Thomas C.,Choi, Woo-Baeg
, p. 1523 - 1532 (2007/10/02)
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.
