The selective C–H carbonylation of methylene bonds, in the presence of traditionally more reactive methyl C–H and C(sp2)–H bonds, in α-tertiary amines is reported.

Complex CpRuCl(PPh 3) 2 catalyzes reactions of terminal alkynes with 4-picoline N-oxide and primary and secondary amines to afford the corresponding amides. The reactions occur in chlorinated solvent and aqua medium showing applications in peptide chemistry. Stoichiometric studies reveal that the true catalysts of the processes are the vinylidene cations [CpRu(=C=CHR)(PPh 3) 2 ] + which are oxidized to the Ru(η 2-CO)-ketenes by the N-oxide. Finally, nucleophilic additions of primary and secondary amines to the free ketenes yield the corresponding amides.

A novel osmium-catalyzed cyclization of o-alkynyl phenethylamines to give 3-benzazepines is reported. The procedure allows the straightforward preparation of a broad range of dopaminergic 3-benzazepine derivatives. Mechanistic investigations revealed that the process takes place via osmacyclopropene intermediates, which were isolated and characterized by X-ray crystallography.

The Ru-catalyzed intramolecular oxidative amidation (lactamization) of aromatic alkynylamines with 4-picoline N-oxide as an external oxidant has been developed. This chemoselective process is very efficient to achieve medium-sized ε- and ζ-lactams (seven- and eight-membered rings) but not for the formation of common δ-lactams (six-membered rings). DFT studies unveiled the capital role of the chain length between the amine and the alkyne functionalities: the longer the connector, the more favored the lactamization process vs hydroamination.