Palladium-Catalyzed Carboauration of Alkynes and Palladium/Gold Cross-Coupling

Abstract

A new palladium-catalyzed syn carboauration of alkynes proceeds in 2 h at ambient temperature with complete regioselectivity. The resulting α-ester vinyl−gold intermediates are resistant to rapid protodemetalation, permitting their participation in new one-pot palladium-and-gold cross-coupling reactions and electrophilic trapping reactions.

Gold‐Catalyzed Intramolecular Oxidative Cross‐Coupling of Nonactivated Arenes

“…The preference for electronrich over electron-poor aryl-substituted allenoates supports a mechanism based on a Friedel-Crafts arylation and argues against a pathway involving an S N Ar-type step by a nucleophilic organogold species. [15] The suitability of AuCl 3 as a catalyst for the reaction (Table 1, entry 1) is consistent with the proposed mechanism. Initial activation of the allenoate by Au III could lead directly to an intermediate of type B, which, upon conversion to the product, generates the proposed catalytic species, Au I .…”

Gold: Migratory Insertion at Au(I)

“…Complex 9 is highly functional and sterically hindered, yet it reacts smoothly and cleanly affording efficient access to trisubstituted olefins with complete regio-and stereo-control (Scheme 4.10). The isolated yields are comparable to those reported by Blum for similar reactions with less substituted vinylgold(I) complexes [20].…”

Bimetallic Catalysis using Transition and Group 11 Metals: An Emerging Tool for CC Coupling and Other Reactions

“…Blum and co- www.chemeurj.org workers have reported the Pdcatalyzed carboauration of alkynes with vinyl-gold triphenylphosphane to produce synalkenyl-gold complexes (Scheme 41), which were characterized by X-ray crystallography on single crystals. [97] Moreover, these isolable gold complexes reacted with suitable electrophiles to yield diand trisubstituted olefins with high regio-and diastereoselectivity. Interestingly, this synthesis could be carried out onepot, and the insensitivity of the reaction to water and oxygen permitted the use of commercial solvents and open glassware.…”