Recent methods for diversification of bile acids and related steroids towards supramolecular.

Bile acids (BAs) are a class of steroidal surfactants that have been studied as building blocks for constructing useful chemical frameworks. These starting materials have rigid structures with defined hydrophobic and hydrophilic faces, which promotes self-assembly in well-defined chemical architectures. The BA scaffolds can undergo a variety of transformations to introduce a range functionalities with practical applications. These functionalized derivatives have seen application in pharmacology, supramolecular chemistry, and nanotechnology in roles such as surfactants, gelators, drug conjugates, or chemical detectors. This review seeks to highlight recent synthetic methods utilizing BAs to construct useful chemical structures and their application in supramolecular chemistry.

Analytical study of superaromaticity in cycloarenes and related coronoid hydrocarbons.

Recently synthesized septulene is a unique cycloarene molecule in that no macrocyclic conjugation circuits can be chosen from the π-system. This molecule has essentially no superaromatic stabilization energy (SSE) and can be viewed as an ideal nonsuperaromatic macrocycle. SSEs for kekulene and other cycloarenes are also very small. In these hydrocarbons, a macrocycle formed by fused benzene rings effectively suppresses not only the aromaticity inherent in macrocyclic (4n+2)-site conjugation circuits but also the antiaromaticity inherent in macrocyclic (4n±1)-site circuits. Comparative study of superaromaticity in multilayered coronoid hydrocarbons revealed that not only SSE but also the HOMO contribution to SSE is minimized in odd-layered coronoids.

Investigation of sp(2)-sp coupling for electron-enriched aryl dihalides under oxygen-free Sonogashira coupling reaction conditions using a two-chamber reaction system.

Triethylamine hydroiodide crystals were formed during Sonogashira reactions; after complete reaction the solution retains a characteristic light color (see picture). Very sluggish Sonogashira reactions of electron-enriched aryl diiodides have been carried out in high yield in an oxygen-free, two-chamber reaction system. The formation of triethylamine hydroiodide crystals was monitored to determine the completion of reaction.