New Synthetic Methodology Using Base-Assisted Diazonium Salts Activation and Gold Redox Catalysis

Over the past two decades, homogeneous Au(I) catalysis has been a valuable synthetic tool for activating a series of unsaturated carbon-carbon bonds towards nucleophilic attack. Despite this progress, Au(I/III) redox chemistry has not been well explored. This is largely due to the challenges associated with the high oxidation potential of gold. Hence, the need for an efficient and safe method for Au oxidation. Herein, a base-assisted diazonium salt activation has been used to facilitate Au redox reactions under mild reaction conditions. This oxidative coupling method afforded functional isoxazolines with good to excellent yields, while the alternative photoactivation method provided trace amounts of the isoxazoline products. This study further broadens the scope of gold redox chemistry. Similarly, cyloporpanol ring opening has been reported under mild chemical condition. This leads to the formation of β-ketones at up to 85% yields. Furthermore, a series of novel triazole based ruthenium alkylidene complexes are reported. The well-defined complexes were employed to catalyze the cross-metathesis reaction of styrene and a series of coupling partners. Like Grubb II catalysts, complex Ru-TA 2 gave 56% E-olefin in a cross-metathesis reaction. For ring opening metathesis reaction, our catalysts give up to 55% Z-olefin. Although, the results obtained for cross metathesis and ring opening metathesis polymerization are like currently reported yields from Grubbs catalyst, a significant structural modification would further improve the selectivity of the catalysts while also increasing yield