No abstract

No abstract

amounts of p-benzoquinone), For example, the oxidation of 1,3-cycloheptadiene by O2 in acetic acid (2 M on LiOAc) at 40 OC catalyzed by 5 mol % each of Co(TPP), hydroquinone, and P~( O A C )~ afforded cis-1,4-diacetoxy-2-cycloheptene (>92% cis) in 65% isolated yield.The corresponding oxidation using Mn(TPP) in place of Co-(TPP) also worked but was considerably slower. For example, the oxidation of 1,3-cyclohexadiene gave only a 56% yield of 1,4-diacetoxy-2-cyclohexene after 48 h, and now the trans/cis ratio was only 72/28.The oxidation described here has similarities with biochemical processes where an oxidation becomes very mild and selective when several redox couples with falling redox potentials are interacting. In many biological systems metalloporphyrins and p-hydroquinoneslp-benzoquinones play important roles as electron carriers. For example, ubiquinones are known to mediate the electron-transfer processes involved in energy production in aerobic organisms. The model system described here is to our knowledge the first example of a selective oxidation using a triple catalysis with oxygen as the ultimate oxidant.

A single‐step synthesis of 1‐adamantylmethyl α‐ and β‐glycosides starting from commercially available peracetylated monosaccharides is reported. The α‐ and β‐glucopyranosides 1a and 1b bind to β‐cyclodextrin with association constants in the order of 105 M−1, as determined by 1H NMR spectroscopy. The carbohydrate moiety contributes to the binding depending on the pyranose stereochemistry. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)