2-Iodoisatogens: versatile intermediates for the synthesis of nitrogen heterocycles.

A Cu-promoted cyclization of 2-nitrophenyl iodoacetylenes provides a direct route to a range of 2-iodoisatogens. These compounds represent useful intermediates for the late-stage elaboration of the C-I bond to furnish isatins and a range of alternative heterocyclic products.

Studies on the stereochemical assignment of 3-acylidene 2-oxindoles.

The designation of E/Z-geometrical isomers in 3-acylidene 2-oxindoles by NMR spectroscopy can lead to erroneous assignment of alkene stereochemistry because of the narrow chemical shift range observed over a large series of analogues. In contrast, UV-Vis spectroscopy offers a convenient and more reliable method for alkene stereochemical assignment. A combination of X-ray crystallography and theoretical studies shows that the observed differences in UV-Vis spectroscopic behaviour relate to the twisted conformation of the Z-isomers that provides reduced conjugation and weaker hypsochromic (blue-shifted) absorbances relative to those of the E-isomers.

Synthesis of ynone trifluoroborates toward functionalized pyrazoles.

The synthesis of a range of novel ynone trifluoroborates has been achieved, in a two-pot process from propargylic alcohols. These alkynes have been subsequently used in the formation of a range of pyrazole trifluoroborate salts via cyclization with hydrazines. The products are generated with high levels of regiocontrol and in excellent yields and represent versatile synthetic intermediates.