Molecular Rods Combining <i>o</i>‑Carborane and Bicyclo[1.1.1]pentane Cages: An Insertion of the Triple Bond Located Next to a Highly Strained Cage

Octacarbonyl dicobalt and bis­(dimethyl sulfide)­decaborane B₁₀H₁₂(Me₂S)₂ were successfully added to 1,3-diethynylbicyclo[1.1.1]­pentane in good yields. This is an interesting example of a cycloaddition reaction achieved next to the bicyclopentane cage that tends to rearrange in many other cases. It proves that both reagents attack the triple bond in a more or less concerted manner that prevents the rearrangement. Products of the latter reaction are of a particular interest because the bicyclopentane and <i>o</i>-carborane cages are immediately linked in their rodlike structures. The new kind of molecular rotors was thus constructed. ¹H and ¹³C nuclear magnetic resonance spectra in solution reveal an averaged rotational symmetry of the molecules with a well-defined geometry that has been confirmed by X-ray structural analysis in several examples

Molecular Rods Combining <i>o</i>‑Carborane and Bicyclo[1.1.1]pentane Cages: An Insertion of the Triple Bond Located Next to a Highly Strained Cage

Octacarbonyl dicobalt and bis­(dimethyl sulfide)­decaborane B₁₀H₁₂(Me₂S)₂ were successfully added to 1,3-diethynylbicyclo[1.1.1]­pentane in good yields. This is an interesting example of a cycloaddition reaction achieved next to the bicyclopentane cage that tends to rearrange in many other cases. It proves that both reagents attack the triple bond in a more or less concerted manner that prevents the rearrangement. Products of the latter reaction are of a particular interest because the bicyclopentane and <i>o</i>-carborane cages are immediately linked in their rodlike structures. The new kind of molecular rotors was thus constructed. ¹H and ¹³C nuclear magnetic resonance spectra in solution reveal an averaged rotational symmetry of the molecules with a well-defined geometry that has been confirmed by X-ray structural analysis in several examples

Phenanthrylene-butadiynylene and Phenanthrylene-thienylene Macrocycles: Synthesis, Structure, and Properties

A series of macrocycles consisting of 9,10-substituted phenanthrenes connected by butadiynylene linkers in positions 3 and 6 has been described as well as their transformation into the corresponding phenanthrylene-thienylene macrocycles. Structure and properties of the macrocycles, such as self-association in solution and optical and electrochemical properties, were studied and reported in a comparative manner with respect to the effects of the different sizes and shapes of the macrocycles and the character and length of their side chains

Silychristin: Skeletal Alterations and Biological Activities

Silychristin is the second most abundant flavonolignan (after silybin) present in the fruits of <i>Silybum marianum</i>. A group of compounds containing silychristin (<b>3</b>) and its derivatives such as 2,3-dehydrosilychristin (<b>4</b>), 2,3-dehydroanhydrosilychristin (<b>5</b>), anhydrosilychristin (<b>6</b>), silyhermin (<b>7</b>), and isosilychristin (<b>8</b>) were studied. Physicochemical data of these compounds acquired at high resolution were compared. The absolute configuration of silyhermin (<b>7</b>) was proposed to be identical to silychristin A (<b>3a</b>) in ring D (10<i>R</i>,11<i>S</i>). The preparation of 2,3-dehydrosilychristin (<b>4</b>) was optimized. The Folin–Ciocalteau reduction and DPPH and ABTS radical scavenging assays revealed silychristin and its analogues to be powerful antioxidants, which were found to be more potent than silybin and 2,3-dehydrosilybin. Compounds <b>4</b>–<b>6</b> exhibited inhibition of microsomal lipoperoxidation (IC₅₀ 4–6 μM). Moreover, compounds <b>4</b>–<b>8</b> were found to be almost noncytotoxic for 10 human cell lines of different histogenetic origins. On the basis of these results, compounds <b>3</b>–<b>6</b> are likely responsible for most of the antioxidant properties of silymarin attributed traditionally to silybin (silibinin)