Biarylphosphonite Gold(I) Complexes as Superior Catalysts for Oxidative Cyclization of Propynyl Arenes into Indan‐2‐ones

Abstract

Striking gold: A series of variously functionalized propynyl arenes was smoothly converted into indan‐2‐ones by a new gold(I)‐catalyzed oxidative cyclization process. [LAu]NTf2 (Tf=trifluoromethanesulfonyl) is a superior catalyst both in terms of yield and kinetics for the present transformation.

Meeting the Challenge of Intermolecular Gold(I)‐Catalyzed Cycloadditions of Alkynes and Allenes

“…48 The synthesis of α-functionalized ketones through this process circumvents the use of hazardous α-diazoketones. The resulting α-oxo gold–carbenes can be trapped intramolecularly by formal O–H,47a, 49 N–H,50 and C–H48b, 51 insertions or by other nucleophilic partners 52. 53 However, it is important to note that in other related cases, the initial involvement of α-oxo gold(I)–carbene has been questioned 54.…”

Formation of Oxazoles from Elusive Gold(I) α‐Oxocarbenes: A Mechanistic Study

“…Hence, in the reaction with pyridine N‐ oxide, pyridine adducts of the formal gold‐α‐oxocarbenes are formed ( Int + in Figure ). A question remains, whether the elusive gold‐α‐oxocarbenes exist as short‐lived intermediates within a solvent cage or whether the reaction proceeds as an S N 2 or S N 2′ substitution of pyridine by the other nucleophile (possible pathways to the grey panel in Figure ).…”

Gold-catalyzed oxidation of propargylic ethers with internal C–C triple bonds: Impressive regioselectivity enabled by inductive effect

“…We [1] have previously showed that via gold-catalyzed [2] intermolecular oxidation [3] of internal alkynes a propargyl moiety can be converted into an enone moiety under exceptionally mild reaction conditions, thereby providing a solution for masking synthetically versatile enones. [1e] Scheme 1 shows a generic reaction with the proposed mechanism outlined.…”