A domino sequence has been developed between vinyldiazoacetates and racemic allyl alcohols, involving five distinct steps. The sequence generates highly functionalized cyclopentanes with four new stereogenic centers as single diastereomers in 64-92% ee. The first step is a rhodium-catalyzed oxygen ylide formation, which is then followed by a [2,3]-sigmatropic rearrangement, an oxy-Cope rearrang...

The 2-carbene tautomer of pyridine (I), azacyclohexanetriene2-ylidene (II), was first proposed by Hammick1 70 years ago to explain the facile decarboxylation of 2-picolinic acid. Recent theoretical calculations2 have shown that II has energy about 4550 kcal‚mol-1 higher than I and that the transition state for the I to II rearrangement lies ca. 85 kcal‚mol-1 above I. Accordingly, the I to II ta...

The relative stability of the normal and tautomeric forms of adenine and thymine has been formerly analysed with semi-empirical and abinitio methods [1—2]. In the same way we have now calculated the charge distribution of several excited states in order to determine the intramolecular charge transfer involved in the tautomerization process. Moreover, we have obtained the direction of the polari...

(a) Draw the bi-molecular complex (see Figure 2 in the paper) using Avogadro. (b) Optimize the structure at B3LYP/6-31G** level of theory. (c) Prepare an input file for a relaxed scan (same level of theory) of the proton transfer using the modredundant option (check the manual page for opt ). Please include the option maxcyc=8 regarding the optimization. (Hint: which geometrical parameter do yo...

Metal-free organic triplet emitters are an emerging class of semiconducting material. Among them, molecules with tunable emission responsive to environmental stimuli have shown great potential in solid-state lighting, sensors, and anti-counterfeiting systems. Here, a novel excited-state intramolecular proton transfer (ESIPT) system is proposed showing the activation thermally activated delayed ...

Thiotropolone isolated in argon and xenon matrices (as monomers) or a neat solid the crystalline amorphous state) at low temperature was found to exist only thione-enol form. Visible light irradiation (λ ≥ 400 nm) leads → thiol-keto tautomerization under conditions 15 K. The assignment of IR spectra two thiotropolone tautomers (thione-enol thiol-keto) carried out with support B3LYP/6-311+G(2d,p...