Gold achiral complexes

Toste has developed an alternative approach to the enantioselective hydroamina-tion of N-allenyl sulfonamides that employs a chiral or achiral gold complex in combination with a chiral phosphonate anion [43]. As an example of this approach, treatment ofy-allenyl sulfonamide 63 with a catalytic 1 1 mixture of the achiral mono (gold) phosphine complex (PMe2Ph)AuCl and chiral, enantiomerically pure silver phosphonate Ag-( J )-64 (5 mol%) in benzene at room temperature for 48 h formed 2-alkenyl pyrrolidine 65 in 84% isolated yield with 99% ee (Eq. (11.36)). 

In recent years, several groups have developed enantioselective tandem reactions based on the combination of gold catalysis and organocatalysis. Among them, Gong et al. reported that an achiral gold complex compatibly worked with a chiral phosphoric acid to promote a domino intramolecular hydroamination-reduction reaction, readily transforming... 

Han Z-Y, Xiao H, Chen X-H, Gong L-Z. Consecutive intramolecular hydroamination/asymmetric transfer hydrogenation under relay catalysis of an achiral gold complex/chiral brpnsted acid binary system. J. Am. Chem. Soc. 2009 131 9182-9183. 

Toste and coworkers have developed effective gold(I)-catalyzed protocols for the intramolecular enantioselective hydroalkoxylation of y- and 8-hydroxy allenes employing chiral, enantiomerically pure silver salts [107]. For example, treatment of y-hydroxy allene 66 with a catalytic 1 2 mixture of the achiral bis(gold) complex (dppm)Au2Cl2 [dppm = bis(diphenylphosphino)methane] and chiral silver phos-phonate Ag-(J )-67 in benzene at room temperature led to isolation of 2-alkenyl tetrahydrofuran 68 in 90% yield with 97% ee (Eq. (12.36)). A combination of chiral bis(gold) complex with a chiral silver salt proved effective for terminally unsubstituted allenyl alcohols. For example, reaction of 5,6-heptadienol catalyzed by a mixture of [(S,S)-DIPAMP]Au2Cl2 [DIPAMP = l,2-ethanediylbis[(2-methoxyphenyl) phenylphosphine] and Ag-(J )-67 gave 2-vinyltetrahydropyran 69 in 96% yield with 92% ee (Eq. (12.37)). 

In 2013, Gong et al. reported a relay catalytic domino hydroamination-redox reaction, which was able to directly assemble tertiary amine substituted 3-en-l-yne derivatives and anilines into the corresponding cyclic aminals by using a gold(i) complex and an achiral phosphoric acid." By using a chiral phosphoric acid, the authors have developed an enantioselective version of this reaction. As shown in Scheme 7.32, the reaction of l-(2-ethynylphenyl)pyrrolidine and p-anisidine in the presence of a catalytic combination of a chiral phosphoric acid and Ph3PAuNTf2 led to the... 

Zhang Z, Lee SD, Widenhoefer RA. Intermolecular hydroa-mination of ethylene and 1-alkenes with cyclic ureas catalyzed by achiral and chiral gold(I) complexes. J. Am. Chem. Soc. 2009 13(15) 5372-5373. 

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