A new Pd-catalyzed autotandem process is presented by the reaction of tosylhydrazones of cyclic ketones and 2,2'-dibromobiphenyls and related systems. The process involves cross-coupling with tosylhydrazone followed by an intramolecular Heck reaction and gives rise to spirocyclic structures. Noteworthy, two C-CAr bonds are formed on the hydrazonic carbon during the process. Depending on the starting dibromide, an array of spirofluorenes, spirodibenzofluorenes, spiroacridines, and spiroanthracenes have been prepared. Thus, this methodology may be applied for the preparation of interesting structures useful in the development of optoelectronic materials.

1,3-Diaryl-3-trifluoromethylcyclopropenes and 2-aryl- or 2-alkyl-1,3-diaryl-3-trifluoromethylcyclopropenes are prepared in a very simple way by reaction between 1,1,1-trifluoroacetophenone tosylhydrazones and terminal or internal alkynes, respectively, in a base promoted process that does not require the presence of any metal catalyst. The essential role of the trifluoromethyl group, which enables the formation of the cyclopropenes instead of the expected pyrazoles, has been computationally investigated, suggesting the participation of a free carbene.

The Pd-catalyzed reaction between 2,2'-dibromobiphenyls and related systems with tosylhydrazones gives rise to new π-extended conjugated polycarbo- and heterocycles through an autotandem process involving a cross-coupling reaction followed by an intramolecular Heck cyclization. The reaction shows wide scope regarding both coupling partners. Cyclic and acyclic tosylhydrazones can participate in the process. Additionally, a variety of aromatic and heteroaromatic dibromoderivatives have been employed, leading to an array of diverse scaffolds featuring a fluorene or acridine central nucleus, and containing binaphthyl, thiophene, benzothiophene and indole moieties. The application to appropriate tetrabrominated systems led to greater structural complexity through two consecutive autotandem cascades. The photophysical properties of selected compounds were studied through their absorption and emission spectra. Fluorescence molecules featuring very high quantum yields were identified, showing the potential of this methodology in the development of molecules with interesting optoelectronic properties.

A new method for the synthesis of polysubstituted conjugated dienes is described, through the palladiumcatalyzed cross-coupling between N-tosylhydrazones and alkenyl bromides. The reaction proceeds efficiently when a combination of a highly substituted bromoalkene and a hydrazone derived from a ketone are employed, pointing to the convenience of a sterically encumbered environment. This unprecedented process allows for the stereocontrolled preparation of highly substituted dienes and polyenes.

The reaction between g-azido-N-tosylhydrazones and boronic acids leads to the obtention of 2,2-disubstituted pyrrolidines in adomino process that includes 1) diazoalkane formation, 2) intermolecular carboborylation of the diazocompound, and 3) intramolecular carborylation of the azide, and comprises the formation of aC sp 3 À Csp 3 and aC sp 3 À N bonds on the same carbon atom. The reaction proceeds without the need of any transition-metal catalyst under microwave activation and features wide scope in both reaction partners.It can be applied to both alkyla nd arylboronic acids with equal efficiency.W ith N-tosylhydrazones derived from 2-(2-azidoethyl)-cyclopentanone and cyclohexanone the reactions are highly diastereoselective leading to the cis-fused bicyclic systems as unique diastereoisomers.T he scope of the process is illustrated by over sixty examples,including scaffolds present in natural alkaloids,and the mechanistic proposal is suppported by DFT-based computations.