Obolactone

Obolactone 화학적 특성, 용도, 생산

• Synthesis

  The synthesis of (+)-obolactone (14, Scheme 3) by Brückner and Walleser employed the same conditions from the synthesis of 17-deoxyroflamycoin to transform bis-epoxide R,R-4 to bis-homoallylic diol S,S-8.  Diol 8 was then protected using 2,2-dimethoxypropane under acidic conditions to provide acetonide 12 in 95% yield. One of the alkene functional groups of the C2- symmetric acetal underwent a subsequent symmetry-breaking Wacker oxidation. Treatment of acetonide 12 with catalytic PdCl2 under an atmosphere of oxygen using CuCl as the stoichiometric oxidant afforded a 64% yield of methyl ketone 13, with over-oxidation to the diketone also observed (18% yield). The methyl ketone functionality of 13 was critical for the installation of the dihydro-g-pyranone moiety in the natural product, while the syn-orientation of the C–O bonds was achieved through Mitsunobu inversion of the lactone stereocenter. Brückner and Walleser specifically mention that while Krische and co-workers have reported on an impressive single-step procedure for the catalytic enantioselective synthesis of bishomoallylic diol (S,S-4) from 1,3-propanediol, and have used this method extensively in the synthesis of polyketide natural products, 21,22 the high cost of catalyst and ligand precluded their use on scale in this case.
  

Obolactone 공급 업체

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