Tert-Butyl hydroperoxide-pyridinium dichromate: a convenient reagent system for allylic and benzylic oxidations

Regio‐ and Stereospecific Synthesis of Cholesterol Derivatives and Their Hormonal Activity in Caenorhabditis elegans

“…Allylic oxidation of cholesteryl acetate using Chandrasekaran's procedure provided 7-ketocholesteryl acetate (27). [57] Catalytic hydrogenation of 27 to the saturated ketone 28 and subsequent reduction with lithium aluminum hydride led directly to the 7α-alcohol 26a and the 7β-alcohol 26b which were separated by flash chromatography. Ester cleavage of compound 28 afforded 7-keto-5α-cholestan-3β-ol (29).…”

Supported Gold Nanoparticles Catalysts for Solvent-free Selective Oxidation of Benzylic Compounds into Ketones at 1 atm O2

“…Conventionally, stoichiometric amount of oxidants such as manganese dioxide, selenium dioxide or chromium trioxide and homogeneous catalytic methods are employed for these transformations [1][2][3][4][5][6]. Yet, excessive use of these reagents, along with difficult work-up of the hazardous metal residues and lack of recyclability of homogeneous catalytic systems makes such procedures environmentally objectionable.…”

“…Reaction conditions: m(substrate) = 1 g; m(Au/TiO 2 ) = 50 mg; t = 24 h; entries (1-4,6,7), T = 90°C; entries(5,8),…”

Bismuth-catalyzed allylic oxidation using t-butyl hydroperoxide

“…Of greater preparative interest has been the use of hydroperoxides combined with different types of metal catalysts [5][6][7][8][9][10] to prepare allylic oxidation products from D 5 -steroids. Despite the good yields reported with CrO 3 , 5 hexacarbonylchromium Cr(CO) 6 , 6 pyridinium dichromate 7 and RuCl 3 , 8 the toxicity of these chromium compounds and the high cost of the ruthenium catalyst led us to search for more environmentally acceptable methods based on the use of copper 9 and cobalt 10 catalysts.…”

“…Despite the good yields reported with CrO 3 , 5 hexacarbonylchromium Cr(CO) 6 , 6 pyridinium dichromate 7 and RuCl 3 , 8 the toxicity of these chromium compounds and the high cost of the ruthenium catalyst led us to search for more environmentally acceptable methods based on the use of copper 9 and cobalt 10 catalysts. However, a difficult separation step is needed to remove such catalysts, which cannot easily be recovered and reused.…”