7 research outputs found
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 B<sub>10</sub>H<sub>12</sub>(Me<sub>2</sub>S)<sub>2</sub> 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. <sup>1</sup>H and <sup>13</sup>C 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 B<sub>10</sub>H<sub>12</sub>(Me<sub>2</sub>S)<sub>2</sub> 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. <sup>1</sup>H and <sup>13</sup>C 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 (IC<sub>50</sub> 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)