Catalysis mediated by Au(I) and Au(III) complexes has recently received great attention as an emerging tool for the various useful organic transformations. Typically employed catalytic systems are AuCl3 or the combined use of a phosphine Au(I) chloride and a silver salt. We projected that appropriate choice of phosphine ligand could have a direct impact on the reactivity, especially in case where the reactivity is not sufficient. However, there have been limited studies on enhancing catalytic activity of Au complexes by changing steric and/or electron-demand of ligand systems, although it is highly desirable considering the high cost of gold complexes. In quest for the more reactive species, we describe herein a tris-(pentafluorophenyl)phosphine gold(I) chloride in the presence of silver salts, as new efficient catalytic system and report our preliminary results of oxycarbonylation of carbonates derived from homopropargyl alcohol. In our previous work on gold(III) catalyzed cyclization of tert-butyl allenoates, we have noted that the activity of Au(III) complex is greatly affected by the choice of ligand (Table 1): electron-density on phosphorus directly affects the conversion. For example, when triphenylphosphine was used along with AuCl3, no reaction occurred after a prolonged heating. Use of electron-deficient tris-(pentafluorophenyl)phosphine ligand increased the yield up to 85% (isolated yield) in 2 h, almost fully restoring the original reactivity of AuCl3. Encouraged by the result, we were intrigued by the possibility of tuning the reactivity in a more general context of gold catalysis. The synthesis of phosphine gold(I) complexes is shown in Scheme 1. By analogy with the report by Gagosz for the preparation of triphenylphosphine gold(I) bis-(trifluoromethanesulfonyl)imidate, we have treated chlorodimethylsulfide gold(I) with tris-(pentafluorophenyl)phosphine (1 equiv.) at rt in CH2Cl2 (Scheme 1). After concentration and precipitation with excess n-hexane, the desired Au{P(C6F5)3}Cl complex 1a was obtained in 86% yield as air-stable and nonhygroscopic powder. P NMR (121 MHz, CDCl3) indicates peak centered at –32.3 ppm. Further treatment of this complex with AgNTf2 in CH2Cl2 led to the corresponding NTf2 complex 2a ( P NMR: δ −39.6) in 85% yield, after filtration of the insolubles and evaporation to dryness. Based on the high “alkynophilicity” of gold(I) complexes, we set out to examine the oxycarbonylation of tert-butyl carbonate 3a derived from homopropargyl alcohol under the various conditions (Table 2). The resulting product has protected aldol synthon, thus the current reaction constitutes an important surrogate aldol reaction. A related reaction using stoichiometric amount of IBr has been known for some time, but the corresponding catalytic version is unprecedented as far as we are aware.