Reactivity of phenoxathiin-based thiacalixarenes towards -nucleophiles.

A starting thiacalix[4]arene can be easily transformed into oxidized phenoxathiin-based macrocycles 9 and 9', representing an unusual structural motif in calixarene chemistry. The presence of electron-withdrawing groups (SO, SO) and the considerable internal strain caused by the condensed heterocyclic moiety render these molecules susceptible to nucleophilic attack. The reaction with various organolithium reagents provides a number of different products resulting from the cleavage of either the calixarene skeleton or the phenoxathiin group or both ways simultaneously.

Exploring the Reactivity of Flavins with Nucleophiles Using a Theoretical and Experimental Approach.

Covalent adducts of flavin cofactors with nucleophiles play an important role in non-canonical function of flavoenzymes as well as in flavin-based catalysis. Herein, the interaction of flavin derivatives including substituted flavins (isoalloxazines), 1,10-ethylene-bridged flavinium salts, and non-substituted alloxazine and deazaflavin with selected nucleophiles was investigated using an experimental and computational approach. Triphenylphosphine or trimethylphosphine, 1-nitroethan-1-ide, and methoxide were selected as representatives of neutral soft, anionic soft, and hard nucleophiles, respectively.

Synthesis of Thiapillar[6]arenes Bearing Redox-Active (Hydro)quinone Groups. Electrochemical and XRD Study.

Pillar[]arenes are among the newest members of the macrocyclic family. Nevertheless, their conformational behavior and binding properties as well as redox properties of dealkylated pillar[]arenes are well-studied. At the same time, introducing a heteroatom into a cyclophane macrocycle is already known to alter all the above properties drastically.

Stereoselective oxidation of phenoxathiin-based thiacalix[4]arenes - stereomutation of sulfoxide groups.

A phenoxathiin-based macrocycle represents an inherently chiral building block, well accessible in two steps from the starting thiacalix[4]arene. The oxidized derivatives bearing one sulfoxide group and three sulfonyl groups were found to exhibit unexpected stereochemical preferences of the sulfoxide group during transformations. The sulfoxide moiety is always pointing out of the cavity (SO ), while the opposite (SO ) configuration was never obtained by direct oxidation.

The Unexpected Chemistry of Thiacalix[4]arene Monosulfoxide.

Thiacalix[4]arene monosulfoxide possesses a very unusual chemistry, as demonstrated by several unprecedented derivatives in calixarene chemistry. Interestingly, compound cannot be prepared by the dealkylation of its corresponding tetramethoxy derivative using BBr. Instead, the borate complex is formed with a boron bound by the two neighboring phenolic oxygens and a sulfoxide group.