Metallation of N-vinylpyrroles and -indoles with Hg(OAc)2: N-vinyl vs. pyrrole nucleophilic sites.

N-Vinylpyrroles and -indoles bearing electron-withdrawing substituents at the pyrrole ring are mercurated, with 1 equivalent of Hg(OAc)(2) in dry MeCN (20-80 °C), regioselectively at the vinyl group (yields are almost quantitative), while their congeners without electron-withdrawing functions are mercurated both at the N-vinyl group and the pyrrole ring.

General route to symmetric and asymmetric meso-CF3-3(5)-aryl(hetaryl)- and 3,5-diaryl(dihetaryl)-BODIPY dyes.

A general efficient route to hitherto inaccessible symmetric and asymmetric meso-CF(3)-BODIPY dyes has been developed. The key stages include the reduction of available 2-trifluoroacetylpyrroles to the corresponding alcohols which are further condensed with pyrroles. The method allows the BODIPY with 3(5)aryl(hetaryl) and 3,5-diaryl(hetaryl) substituents to be readily assembled.

C-H...N and C-H...O intramolecular hydrogen bonding effects in the 1H, 13C and 15N NMR spectra of the configurational isomers of 1-vinylpyrrole-2-carbaldehyde oxime substantiated by DFT calculations.

According to the (1)H, (13)C and (15)N NMR spectroscopic data and DFT calculations, the E-isomer of 1-vinylpyrrole-2-carbaldehyde adopts preferable conformation with the anti-orientation of the vinyl group relative to the carbaldehyde oxime group and with the syn-arrangement of the carbaldehyde oxime group with reference to the pyrrole ring. This conformation is stabilized by the C-H..

Conformational study of 2-arylazo-1-vinylpyrroles.

Conformational study of 2-phenylazo-1-vinylpyrrole and 2-(4-bromophenyl)azo-5-methyl-1-vinylpyrrole was performed on the basis of the experimental measurements and high-level ab initio calculations of their 13C--13C and 13C--1H spin-spin coupling constants, showing marked stereochemical behaviour upon the internal rotation of the vinyl group and the pyrrolyl moiety. In liquid phase, both compounds were found to adopt predominant s-trans-s-trans conformation with the noticeable population (ca. 30%) of the higher-energy s-cis-s-trans conformation in the latter compound.