Triphenylphosphine-m-sulfonate/carbon tetrabromide as an easily recoverable catalyst system for the efficient synthesis of xanthene and xanthenone derivatives under solvent-free conditions

Insight into and Computational Studies of the Selective Synthesis of 6H-Dibenzo[b,h]xanthenes

“…Several procedures have been described for the preparation of type 1 xanthenes (Figure ), most of them based on a two- or three-component reaction of β-naphthol with aldehydes. − When naphthoquinones are fused to the xanthenes, two subclasses of products might be produced, which have also been prepared by several synthetic methods (Figure ): benzoxanthenes with one naphthoquinone moiety, represented by compound 2 and its isomer 3 and compound 4 and its isomer 5 , − and dibenzoxanthenes with two naphthoquinone moieties attached to the central pyran ring, which can have three possible isomers, 6–8 . Tisseh et al were the first to report a simple and efficient method for the preparation of dibenzoxanthene derivatives under solvent-free conditions (10 mol % p -toluenesulfonic acid), which they assumed to be the [ b , i ] isomers, but the products suffered from very poor spectroscopic characterization .…”

Multicomponent Coupling Reaction Using Arynes: Synthesis of Xanthene Derivatives

“…In conclusion, we have developed the multicomponent coupling reaction for the synthesis of xanthene derivatives. Most of the synthetic approaches to the benzo-fused oxygen heterocycles have involved the use of phenol derivatives . Therefore, new approaches using transition-metal-catalyzed aromatic C–O bond formation continues to attract much interest .…”