Synthesis and Functionalization of Isomeric Sesquihomodiamantenes.

anti- and syn-sesquihomodiamantenes (SDs) were prepared and structurally characterized. anti-SD and parent sesquihomoadamantene were CH-bond functionalized by utilizing a phase-transfer protocol. The density functional theory-computed ionization potentials of unsaturated diamondoid dimers correlate well with the experimental oxidation potentials obtained from cyclic voltammetry. Similar geometries ensue for both the reduced and ionized SD states, whose persistence is supported by the ß-hydrogen's spatial sheltering. This makes SDs promising building blocks for the construction of diamond materials with high stability and carrier mobility.

Synthetic Doping of Diamondoids through Skeletal Editing.

We present a strategy for the skeletal editing of diamondoid structures to selectively displace methylene for heteroatom moieties in the carbon framework. This constitutes a synthetic approach to doping diamond-like structures with electron donor dopants (O, N, and S). The key steps involve two subsequent retro-Barbier fragmentations followed by cage reconstruction in the presence of a dopant. Remarkably, the incorporation of n-dopants reduces the strain of the diamondoid cage as shown through homodesmotic equations.

N-Alkoxyimidazolylidines (NOHCs): nucleophilic carbenes based on an oxidized imidazolium core.

We report the first preparation of N-alkoxyimidazolylidene (NOHC), a nucleophilic carbene based on an oxidized imidazolium core. The Arduengo-type analogous carbene center shows the most upfield 13C NMR shift compared to common NHCs. The obtained gold(I) complex of the carbene follows the 13C NMR upfield trend and shows the marked influence the alkoxy substituents. Similarly, the 77Se and 15N NMR shifts of a range of NOHC-selenium adducts show increased σ-donation and decreased π-back donation in the bonding with the nucleophile. This extension of the NHC family provides altered electronic properties for the use of such carbenes as ligands or catalysts.

Synthesis and antiproliferative activity of hindered, chiral 1,2-diaminodiamantane platinum(II) complexes.

Platinum-based antineoplastic agents play a major role in the treatment of numerous types of cancer. A new bulky, lipophilic, and chiral ligand based on 1,2-diaminodiamantane in both of its enantiomeric forms was employed for the preparation of new platinum(ii) complexes with chloride and oxalate ligands. The dichloride complexes have a higher solubility and were evaluated as anti-proliferation agents for human ovarian cancer cell lines A2780 and cisplatin-resistant A2780cis. Its R,R-enantiomer showed increased efficacy compared to cisplatin for both cancer cell lines. A chromatographic approach was used to estimate the solvent partition coefficient of the dichloride complex. The binding of diamondoid-based platinum complexes to nucleotides was tested for both enantiomers with guanosine monophosphate (GMP) and deoxyguanosine monophosphate (dGMP) and occurs at a similar or faster rate for both isomers compared to cisplatin despite greatly increased steric demand. These findings highlight the potential in 1,2-diaminodiamantane as a viable pharmacophore.