Total synthesis of hemibrevetoxin B and (7a.alpha.)-epi-hemibrevetoxin B

Nicolaou, K. C.; Reddy, K. Rajender; Skokotas, G.; Sato, Fuminori; Xiao, Xiao Yi; Hwang, Cheol Kyu

doi:10.1021/ja00062a021

Cited by 121 publications

(53 citation statements)

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“…The catalytic hydrogenation of azide 16 followed by the reaction of the resulting amine with phenyl chloroformate afforded the carbamate 17 . The cleavage of the isopropylidene acetal with trifluoroacetic acid in water 30 afforded only a low yield of the unprotected diol. A more suitable method for our substrate proved to be the use of an aqueous solution of oxalic acid in tetrahydrofuran that directly provided the cis - 10 oxazolidinone after a basic work up.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Stereospecificity of 4,5-Disubstituted Oxazolidinone Ligands Binding to T-box Riboswitch RNA

et al. 2011

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The enantiomers and the cis isomers of two previously studied 4,5-disubstituted oxazolidinones have been synthesized and their binding to the T-box riboswitch antiterminator model RNA investigated in detail. Characterization of ligand affinities and binding site localization indicate that there is little stereospecific discrimination for binding antiterminator RNA alone. This binding similarity between enantiomers is likely due to surface binding, which accommodates ligand conformations that result in comparable ligand-antiterminator contacts. These results have significant implications for T-box antiterminator-targeted drug discovery and, in general, for targeting other medicinally relevant RNA that do not present deep binding pockets.

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Section: Resultsmentioning

confidence: 99%

Synthesis and Stereospecificity of 4,5-Disubstituted Oxazolidinone Ligands Binding to T-box Riboswitch RNA

et al. 2011

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“…A subsequent selective desilylation [33] with CSA in a mixture of methanol and CH 2 Cl 2 led to the primary alcohol 32. Oxidation of 32 to form aldehyde 33 was accomplished with TPAP.…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis of Salicylihalamides A and B

Herb

Bayer

Maier

2004

Chemistry A European J

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The paper illustrates two efficient routes to macrolactone 19 containing a 3-(para-methoxybenzyloxy)propyl side chain at C-15. The chiral center at C-15 was introduced by a Noyori reduction of keto ester 5. The intermediate common to both routes, aldehyde 8, was prepared from keto ester 5. The subsequent chain extension utilized Evans aldol reactions. The first route leads to the alkene 14, which was used, after hydroboration, for a Suzuki cross-coupling reaction with vinyl iodide 15. The derived seco acid 18 was converted into the macrolactone 19 by a Mitsunobu lactonization by using immobilized triphenylphosphine. Alternatively, an aldol reaction of 8 with the 4-pentenoyl derivative 20 was used to prepare alkene 26. This building block led to ester 28, which could also be converted into macrolactone 19 by the classical ring-closing metathesis. After conversion of the C-15 side chain to the corresponding aldehyde, the enamide was introduced through hemiaminal formation and formal elimination of water. Separation of the double-bond isomers and removal of the silyl protecting groups provided salicylihalamides A (E)-1 and B (Z)-1.

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“…Parikh–Doering oxidation and Wittig coupling using phosphonium salt 64 gave the corresponding Z -alkene and 65 following oxidative elimination of the phenyl selenide. xlix As has been reported previously, l the selective removal of the 1° TBDPS group in the presence of the 2° and 3° TBS groups was accomplished using buffered TBAF. Oxidation of the resulting 1° alcohol and Horner–Emmons reaction with the lithium salt of phosphonate 66 gave 67 in 85% yield for the two steps.…”

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confidence: 84%