AuCl /AgSbF

Allenedienes 106 were submitted to a [4+3] intramolecular cycloaddition in presence of a [AuCl(lPr)]/AgSbF catalytic system (Scheme 5.28) [28]. The cycloaddition adducts 107 and/or 108 were obtained in good yields at room temperature. In contrast, this cycloaddition reaction requires a much higher temperature (110°C) when PtCl is employed as the catalyst [29]. This fact shows that the use of [AuCl(IPr)]/AgSbF catalytic system is critical for the success of this cycloaddition. 

The hydration of C-C triple bonds represents one of the most atom economical and environmentally friendly oxidation reactions [37], Recently, Nolan and co-workers reported the cationic [Au(lPr)][SbF ] system, which was generated in situ from [AuCl(lPr)] and AgSbF. The catalyst system showed remarkable activity in the hydration of a large range of alkynes, at An loadings as low as 10 ppm (typically 50-100 ppm), under acid-free conditions (Table 10.6) [38],... 

Table 10.6 [AuCl(IPr)]/AgSbF catalysed hydration of alkynes [38] ...

Am Chem Soc 129 5828 2007]. JohnPhos-AuCl and related complexes, in the presence of AgSbFs (i.e. the SbFs salts), catalyse intramolecular [4+2] cycloadditions of 1,3-enynes or atylalkynes and alkenes with high efficiency [Nieto-Oberhuber et al. J Am Chem Soc 127 6168 2005]. 

In a related study, Uemura and co-workers obtained planar-chiral isochromene chromium complexes by gold-catalyzed enantioselective cyclization of prochiral (l,3-dihydroxymethyl-2-alkynyl)benzene chromium complexes. " The highest selectivities in this 6-e <3to-dig-hydroalkoxylation were observed in the presence of a chiral cationic gold catalyst prepared in situ from (/ )-xylyl-BINAP(AuC1)2 and AgSbFs. With (/ )-SEGPHOS(AuCl)2 and AgBp4, the enantiomeric product was obtained, albeit with low enantioselectivity. 

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