Magnesium oxide catalysts were used to investigate the influence of novel preparative techniques for surface site control on activity.

Thermally induced cycloisomerization reactions of 1,6-allenynes gives α-methylene-γ-lactams via intramolecular Alder-ene reactions. The mechanism is supported by computational and deuterium labelling studies. This thermal, non-radical method enables the discovery of a hitherto unknown route that proceeds via a divergent mechanism distinct from the previous [2 + 2] cycloisomerization manifold.

Herein we report the formation of pyrrolines and tetrahydropyridines from the cyclisation reactions of β-amino allenes by both AuI and AgI catalysts in yields ranging from 5 to 70 %. AuI catalysts favour a 5-endo-dig cyclisation before rapid rearrangement to the 5-exo-dig product, while AgI favours a 6-endo-trig cyclisation. We also report the first known Ag2O catalysed cyclisation reaction of an allene which occurred in good yield (61 %).

A nickel-catalyzed tetradehydro-Diels–Alder reaction of (E)-3-ene-1,8-diynes for the preparation of isoindolines, dihydroisobenzofurans, and tetrahydroisoquinolines has been developed. A series of air-stable nickel catalysts were used in this study, including the novel nickel(0)–phosphite catalysts, Ni[P(O-3,5-Me-Ph)3]4, Ni[P(O-1-naphthyl)3]4, and Ni[P(O-2-naphthyl)3]4. To help understand the type of intermediate in the initial cycloisomerization process, the trapping of nickellacycle intermediates with pinacolborane to yield vinyl boronates is also discussed.