Syntheses of Dimeric Tetrahydroxanthones with Varied Linkages: Investigation of “Shapeshifting” Properties

Abstract

The 2,4′- and 4,4′-linked variants of the cytotoxic agent secalonic acid A and their analogues have been synthesized. Kinetic resolution of an unprotected tetrahydroxanthone scaffold followed by copper-mediated biaryl coupling allowed for efficient access to these compounds. Evaluation of the “shapeshifting” properties of 2,2′-, 2,4′-, and 4,4′-linked variants of the secalonic acids A in a polar solvent in conjunction with assays of the compounds against select cancer cell lines was conducted to study possible correlations between linkage variation and cytotoxicity.

α-Pyrone derivatives, tetra/hexahydroxanthones, and cyclodepsipeptides from two freshwater fungi

“…Interestingly, the dimeric tetrahydroxantione class of compounds, such as 13, seems to be attracting interest of the synthetic community. 24 The current study is another demonstration 4 that understudied biodiversity, regardless of its proximity to urban vs rural vs extreme locations, often reveals new chemical diversity.…”

“…Compound 14 was reported recently by synthesis and was described using the name (-)-blennolide B. 24 (-)-Blennolide B is an enantiomer of the natural blennolide B (which is dextro rotatory). 25 Due to this confusion with the trivial name, and because this is the first isolation of the natural product, we believe that 10hydroxyblennolide H is a more appropriate and understandable name.…”

Xanthones and Cancer: from Natural Sources to Mechanisms of Action

“…From salicylic acid and phenol in phosphorus pentoxide-methanesulfonic acid [144,170] Benzoxanthone FeCl 3 -Catalyzed, three-components, one-pot [171] Caged xanthones Regioselective Claisen/DielsÀ Alder cascade reaction [151,[172][173][174]175] Haloxanthones From 2-bromofluorobenzenes and salicylaldehydes via palladium-catalyzed acylation-SNAr [167,176,177] Hydroxyxanthone Classical one-step synthesis starting from two aryls induced by Mannich reaction and Eaton's reagents. [167,[178][179][180][181][182] Pyranoxanthones From 1,3-dihydroxyxanthone with different reagents [180] Pyridyl xanthones Ag 2 CO 3 mediated oxidative cyclization [183] Sulfonamides xanthones Eaton's reagent and chlorosulfonic acid [184] Thioxanthones Heteropoly acid, catalytic, under microwave [176,185,186] Toxyloxanthones Regioselective aryne addition and Claisen rearrangement [187] Triazole xanthone…”

Enantioselective Total Synthesis of Chromanone Lactone Homo‐ and Heterodimers

“…On the other hand, Porco Jr. et al. prepared 2–4′‐linked tetrahydroxanthones employing a mixture of the corresponding 2‐ and 4‐stannylated monomeric chromanones . Following these lines we used a statistical approach anticipating that the two diastereomeric substrates 21 and 23 should have the same reactivity in the dimerization process.…”

“…prepared 2-4'-linked tetrahydroxanthones employing am ixture of the corresponding 2-and 4-stannylated monomeric chromanones. [19] Following these lines we used as tatistical approach anticipating that the two diastereomerics ubstrates 21 and 23 should have the same reactivity in the dimerization process. Thus, in the reaction of a1 :1-mixture of 21 and 23 using ao ne pot borylation/Suzuki-Miyaura reaction with Pd(OAc) 2 ,B 2 pin 2 and SPhos we expected the formation of homodimers 22 and 24 and heterodimer 25 in a1 :1:2-ratio together with dehalogenated monomeric compounds 19 and 20 (Scheme 4).…”