A mild, catalytic, and highly selective method for the oxidation of alpha,beta-enones to 1,4-enediones.
A new and simple method is described for the one-step oxidation of alpha,beta-enones to 1,4-enediones in good yields (generally 80-90%) using t-butylhydroperoxide as stoichiometric oxidant and 20% Pd(OH)2 on carbon (5 mol %) as catalyst in CH2Cl2 solution. The same reagents have been used to convert ethylene ketals of alpha,beta-enones to the corresponding monoethylene ketals of 1,4-enediones. Seven representative examples are presented in Table 1. All of the available evidence on these oxidations points to a radical-chain mechanism initiated by the tert-butylperoxy radical (see Scheme 1). gamma-tert-Butylperoxy ethers are formed as major products in the oxidation of alpha,beta-enones possessing only a single gamma-hydrogen.
Yu
Jin-Quan
JQ
Department of Chemistry, Cambridge University, Cambridge CB2 1EW, United Kingdom.
Corey
E J
EJ
D000475:Alkenes / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D006878:Hydroxides / Q000737:chemistry; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D010165:Palladium / Q000737:chemistry; D020122:tert-Butylhydroperoxide / Q000737:chemistry
D000475:Alkenes; D006878:Hydroxides; D007659:Ketones; D010165:Palladium; D020122:tert-Butylhydroperoxide