Easy access to pharmaceutically relevant heterocycles by catalytic reactions involving α-imino gold carbene intermediates

Transition Metal-Catalyzed Tandem Reactions of Ynamides for Divergent N-Heterocycle Synthesis

“…Similar to the aforementioned transition metal-catalyzed oxygen transfer reactions of alkynes, the relevant nitrene transfer reactions have also received much attention, as this strategy provides rapid access to a wide range of synthetically useful nitrogen-containing molecules . Among these, gold-catalyzed nitrene transfer reactions based on azides, presumably through α-imino gold carbenes, are particularly attractive, providing great potential for efficient assembly of valuable N-heterocycles (Scheme ).…”

“…The generation of metal carbenes from readily available alkynes through transition-metal catalysis has attracted much attention over the past two decades. , As shown in Scheme , the most general methods for metal carbene formation via this non-diazo approach include the gold-catalyzed 1,6-enyne cycloisomerization, 1,2-acyloxy shift of propargylic carboxylates, alkyne oxidation by N -oxides, and alkyne amination based on azides, , isoxazoles, or sulfilimines . To date, however, only a few methods for the generation of donor/donor metal carbenes, mainly from the transition metal-catalyzed cyclization of enynals or enynones, have been developed.…”

Divergent Gold Catalysis: Unlocking Molecular Diversity through Catalyst Control

“…Gold catalysts, among all other transition metal catalysts, have secured an important position in the field of carbene chemistry. Because of their unique structural features, gold carbenes offer a distinct reactivity and selectivity profile compared to any other transition metal carbenes. − As a result, the past decade has witnessed an exponential growth in the reports of the transformation of gold carbenes. − ,− In 2012, Davies and co-workers reported an enantioselective cyclopropenation reaction of aryl alkyl alkynes and donor/acceptor diazoesters by using the binuclear chiral gold­(I) complex ( S )-xylylBINAP­(AuCl) 2 activated by AgSbF 6 . Interstingly, when alkyne 33b was used in the reaction along with methyl phenyldiazoacetate 33a , an unanticipated bicyclic product 33c was obtained instead of the expected cyclopropenation product (Scheme ).…”

Gold-Catalyzed Synthesis of Small Rings

“…In the same way as α-oxo gold carbenes can be accessed from gold-activated alkynes by oxygen transfer using N -oxides and sulfoxides (see section ), α-imino gold carbenes 439 can be obtained employing nitrogen-based nucleophiles 437 that bear a leaving group on the N atom (Scheme ). − These reagents are also termed nucleophilic nitrenoids, because they perform a net nitrene transfer to the alkyne. Their anti addition to a gold­(I) or gold­(III) activated alkyne delivers vinyl gold species 438 .…”