The Outer‐Sphere Mechanism of Nitrene Transfer onto Gold(I) Alkyne Complexes

Abstract

The recently developed nitrene transfer reaction onto gold‐activated alkynes provides a route to safe and accessible synthons of α‐diazo imides. This reaction is rather unique in that it requires AuI in catalytic amounts; however, this promiscuous metal is only used to activate the alkyne moiety. After such activation is obtained, the nitrene‐transfer process occurs through an outer‐sphere mechanism, in which the metal acts only as a spectator. Density functional theory was applied to elucidate this peculiar reaction and to provide a mechanistic explanation for the experimentally observed isomers at the double bond and imine sites.

Gold-Catalyzed Synthesis of Small Rings

“…Cyclopropanations Involving α-Imino Gold Carbenes. The first example of intermolecular nitrene transfer to gold-activated alkynes, reported by Zhang, 603,604 popularized the use of iminopyridinium ylides such as 452 as nucleophilic nitrenoids. These reagents are the nitrogen analogues of pyridine N-oxides, common oxidants in the field of α-oxo gold carbenes.…”

“…The first example of intermolecular nitrene transfer to gold-activated alkynes, reported by Zhang, , popularized the use of iminopyridinium ylides such as 452 as nucleophilic nitrenoids. These reagents are the nitrogen analogues of pyridine N -oxides, common oxidants in the field of α-oxo gold carbenes. − Combining the use of iminopyridinium ylides and their previously reported oxidative cyclopropanation of 1,5-enynes (see Scheme ), Liu and co-workers described the first cyclopropanation involving α-imino gold carbene intermediates, yielding cyclopropane-fused indanimines 453 (Scheme ).…”