Bile acid chemistry. III. Stepwise side-chain shortening by way of sodium per-iodate oxidation of α-hydroxy bile acids into corresponding aldehydes.

Yanuka, Yehuda; Katz, R. Nathan; Sarel, Shalom

doi:10.1016/s0040-4039(01)99037-9

Cited by 23 publications

(5 citation statements)

References 7 publications

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“…The major product identified was the α,β-unsaturated ketone directly analogous to the ketone side product from Jones oxidation of the ( Z )-alkene (Scheme ). For decarboxylation of α-hydroxy acid 17 , several types of oxidizing reagents failed, including sodium periodate and tetrabutylammonium periodate . Lead(IV) tetraacetate was the only reagent that cleanly gave high yields of the β,γ-unsaturated aldehyde.…”

Section: Resultsmentioning

confidence: 99%

Serine-cis-proline and Serine-trans-proline Isosteres: Stereoselective Synthesis of (Z)- and (E)-Alkene Mimics by Still−Wittig and Ireland−Claisen Rearrangements

Wang

Hart

et al. 2003

J. Org. Chem.

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Two new amide isosteres of Ser-cis-Pro and Ser-trans-Pro dipeptides were designed and stereoselectively synthesized to be incorporated into potential inhibitors of the phosphorylation-dependent peptidylprolyl isomerase Pin1, an essential regulator of the cell cycle. The cis mimic, the (Z)-alkene isomer, was formed through the use of a Still-Wittig [2,3]-sigmatropic rearrangement, while the trans mimic, the (E)-alkene, was synthesized through the use of an Ireland-Claisen [3,3]-sigmatropic rearrangement. Starting from N-Boc-Ser(OBn)-N(OMe)Me, both mimics were synthesized in Boc-protected form suitable for peptide synthesis with an overall yield of 20% in 10 steps for the cis mimic and 13% in eight steps for the trans mimic.

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Section: Resultsmentioning

confidence: 99%

Serine-cis-proline and Serine-trans-proline Isosteres: Stereoselective Synthesis of (Z)- and (E)-Alkene Mimics by Still−Wittig and Ireland−Claisen Rearrangements

Wang

Hart

et al. 2003

J. Org. Chem.

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“…Study of the uncatalyzed reaction mechanism was thus necessary before production of catalytic antibodies. Two mechanisms can be proposed (Scheme ), based on the well-known action of NaIO 4 on α-hydroxy acid, − glyoxylic acid, and phenols 2 Possible Mechanisms of Oxidation of VMA …”

Section: Resultsmentioning

confidence: 99%

Antibody-Catalyzed Decarboxylative Oxidation of Vanillylmandelic Acid

et al. 1998

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The most important industrial process for the synthesis of vanillin is performed in two steps involving an electrophilic aromatic substitution of glyoxylic acid on guaiacol followed by an oxidative decarboxylation of the intermediary α-hydroxy acids formed, thereby producing not only vanillin, but also byproducts which have to be eliminated. In the present study, we took advantage of the high specificity of catalytic antibodies to improve the synthesis of vanillin. Among 11 monoclonal antibodies elicited against the quaternary ammonium hapten H3, antibody H3-12 was found to catalyze the oxidative decarboxylation of vanillylmandelic acid (VMA), the precursor of vanillin, in the presence of sodium metaperiodate. The kinetic data of the antibody-catalyzed reaction are consistent with an ordered binding mechanism. At pH 9.0, H3-12 catalyzed the transformation of VMA into vanillin with a k cat of 2.70 min-1, a Michaelis−Menten constant K a for the binary complex of 260 μM, and a K b for the ternary complex of 2100 μM. The catalyzed reaction was fully inhibited by a hapten analogue with a K i of 10 μM. The fine specificity of anti-H3 monoclonal antibodies was determined using H3-related compounds with a competitive enzyme immunoassay. Controls demonstrating that catalytic activity is actually related to antibody binding, and mechanistic studies, are also presented.

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“…This approach could not be used with substrate 22 because triethylamine, a necessary reagent, was able to induce the elimination of the sulfone and isomerize the olefin to the undesired exocyclic position. As an alternative approach, an oxidative decarboxylaton was considered . With a hydroxy diacid, it should be possible to effect a decarboxylation, a hydration, and a second decarboxylation in one pot to give the desired acid 23a .…”

Section: Completion Of the Synthesismentioning

confidence: 99%

A Versatile Enantioselective Strategy Towardl-C-Nucleosides: A Total Synthesis ofl-Showdomycin

Trost

Kallander

1999

J. Org. Chem.

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Strategies for the synthesis of nucleosides that can provide either L or D isomers become more important as a result of the increasing number of such compounds that are therapeutically useful. The lower toxicity and reduced susceptibility toward metabolism of the L isomers make them particularly interesting. A strategy toward the C-nucleoside analogues has been explored in the context of the synthesis of L-showdomycin. The route involves an asymmetric desymmetrization using palladium catalysis of cis-2,5-diacyloxy-2,5-dihydrofurans available in one step from furan, with carbon nucleophiles. Nucleophilic synthons for a maleimide unit and a methoxycarbonyl unit have been designed. Two sequential palladium-catalyzed reactions introduce both substituents with excellent chemo-, regio-, diastereo-, and enantioselectivity. The presence of a double bond in this doubly alkylated compound at C-3 and C-4 allows easy structural variation. The use of an ester as a hydroxymethyl precursor also introduces a diversity element as well as having importance in its own right. The successful completion of a synthesis of L-showdomycin validates this approach as a viable strategy to C-nucleosides.

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Bile acid chemistry. III. Stepwise side-chain shortening by way of sodium per-iodate oxidation of α-hydroxy bile acids into corresponding aldehydes.

Cited by 23 publications

References 7 publications

Serine-cis-proline and Serine-trans-proline Isosteres: Stereoselective Synthesis of (Z)- and (E)-Alkene Mimics by Still−Wittig and Ireland−Claisen Rearrangements

Serine-cis-proline and Serine-trans-proline Isosteres: Stereoselective Synthesis of (Z)- and (E)-Alkene Mimics by Still−Wittig and Ireland−Claisen Rearrangements

Antibody-Catalyzed Decarboxylative Oxidation of Vanillylmandelic Acid

A Versatile Enantioselective Strategy Towardl-C-Nucleosides: A Total Synthesis ofl-Showdomycin

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