Gold catalysis rearrangements

Rearrangements of 1,3-diynes (43) to dienynes (45a) and (45b) have been carried out catalytically a metal-carbene intermediate (44) is likely to be involved.41 Interestingly, gold catalysis provides mainly (45a) whereas platinum catalysis under a CO atmosphere yields predominantly (45b). 

O-Vinyl oximes prepared from oximes and activated alkynes rearrange with gold catalysis to substituted pyrroles (Scheme 126). °... 

Scheme 7.66 Tandem double Friedel Crafts reaction catalysed by chiral thiourea catalysis and gold catalysis followed by a rearrangement.

A gold catalysis-initiated cascade process toward the synthesis of electron-rich arene-fused hexahydroquinolizinones 131 was developed by Zhang and Liu in 2012 (Scheme 12.57) [62]. In this cascade reaction, a gold-catalyzed amide cyclization to a tethered C-C triple bond initiates a subsequent Frie del-Crafts type cyclization, followed by a Ferrier rearrangement. Synthetic utility of this... 

Recently, allenyl carbinol esters have also been efficiently rearranged into buta-1,3-dien-2-ol esters via metal catalyzed transformations. Gold (1) catalysis has proven efficient under smooth conditions (CH2CI2 at room temperature) when using the biphenylphosphme-based catalyst 173. The stereoselectivity of the process depends on the substrate and favors the formation of the E isomer (Scheme 73) [157]. More recently, the use of rhodium catalysts in similar transformations has been reported to lead to higher E selectivities, although in harsher reaction conditions (Toluene at 120 °C) (Scheme 73) [158]. 

Recently, a multifaceted catalysis approach to substituted pyrroles from ketoximes and alkynes has been reported [46,49,51], O-vinyl ketoximes rearrange in the presence of gold/silver catalyst (PhjPAuCl/AgOTf) in an efficient and regiocon-trolled manner (Scheme 1.144). 

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