Microwave-assisted unimolecular isomerization-Claisen domino reactions of 1,3-di(hetero)aryl propargyl trityl ethers lead, depending on the basicity of the amine, either to the formation of tricyclo[3.2.1.0(2,7)]oct-3-enes (with triethylamine) or to indanes (with DBU). Based upon product analyses and computations, this base dependent dichotomy can be rationalized as a sequel of pericyclic react...

Spiroviolene is a spirocyclic triquinane diterpene produced by Streptomyces violens. Recently, biosynthetic pathway that includes secondary carbocation intermediates and complicated concerted skeletal rearrangement was proposed for spiroviolene, based upon careful labeling experiments. On the basis of density functional theory (DFT) calculations, we propose revised spiroviolene biosynthesis, in...

Using selected theoretical methods the affinity of a large range of Lewis bases towards model cations has been quantified. The range of model cations includes the methyl cation as the smallest carbon-centered electrophile, the benzhydryl and trityl cations as models for electrophilic substrates encountered in Lewis base-catalyzed synthetic procedures, and the acetyl cation as a substrate model ...

The synthesis and characterization of a novel trityl-TEMPO biradical and the investigation of its properties as Dynamic Nuclear Polarization (DNP) polarizing agent are reported. Comparison with a structurally related monoradical (PTM-TEMPE) or mixtures of the two monoradical components reveals that the biradical has a much higher polarization efficiency and a faster polarization buildup. This o...

A diazole is N-substituted with 1-trityl-2-methylaziridine and demethylated and oxidised with NBS under acidic conditions to give a benzimidazolequinone; this novel anti-tumour agent is marginally more cytotoxic than mitomycin C (MMC) towards the normal human fibroblast cell line GM00637, while the MMC-hypersensitive human Fanconi anaemia (FA) cell line, PD20i, lacking the FANCD2 protein, is al...

Several possible routes to obtain an optically active trityl system have been studied. Model systems, using triphenylcarbinol and 4-bromo-^1-chlorotriphenylcarbinol, were employed. Several routes to break down the glycolic acid derivatives of these alcohols were studied. These involve the preparation of the silver salt of the acid and its reaction with bromine; the reaction of the acid with mer...

Hydrophilic photolabile protecting groups (PPGs) for hydroxyl protection have been developed. The new PPGs are derived from 3-(dimethylamino)trityl (DMATr) by replacing the two methyl groups with two hydrophilic butyryl groups. The new PPG reagents can be readily prepared and installed. They are stable in the dark but can be removed cleanly and efficiently in aqueous environments upon irradiati...

A stochastic search procedure for locating energy minimum structures was applied to the sec-butyl cation. A previously unreported structure 3' with strong H-hyperconjugative stabilization of the carbocation center was found at several levels of theory (HF, B3LYP, and MP2). The theoretical equilibrium isotope effect (EIE) for the monodeutero isotopomer of 3' (Keq = 1.4; t = -130 °C) indicates th...