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Four-step Synthesis (four-step + synthesis)
Selected AbstractsEfficient Synthesis of Benzofurans Utilizing [3,3]-Sigmatropic Rearrangement Triggered by N -Trifluoroacetylation of Oxime Ethers: Short Synthesis of Natural 2-ArylbenzofuransEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2007Norihiko Takeda Abstract A new synthetic method for the preparation of benzofurans has been developed. The key step of this method is the [3,3]-sigmatropic rearrangement of N -trifluoroacetyl-ene-hydroxylamines, which was triggered by acylation of oxime ethers. TFAA has been proved to be the best reagent to induce [3,3]-sigmatropic rearrangement for the synthesis of cyclic oracyclic dihydrobenzofurans. On the other hand, the TFAT-DMAP system is found to be the most effective for constructing various benzofurans. Synthetic utility of this reaction is demonstrated by the short synthesis of natural benzofurans without protection of the hydroxy group. The synthesis of Stemofuran A was accomplished via condensation of ketones with aryloxyamine and subsequent reaction with TFAT-DMAP in a four-step synthesis with 72,% overall yield. Similarly, Eupomatenoid 6 and Coumestan were synthesized through the reaction of oxime ether with TFAT-DMAP. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A short synthesis of the parp inhibitor 2-(4-trifluoro-methylphenyl)benzimidazole-4-carboxamide (NU1077)JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2001Steven C. Austen A four-step synthesis of the PARP inhibitor 2-(4-trifluoromethylphenyl)benzimidazole-4-carboxamide (1, NU1077) is presented. Condensation of 2,3-diaminotoluene and 4-trifluoromethylbenzaldehyde afforded 4-methyl-2-(4-trifluoromethylphenyl)benzimidazole. Oxidation of the methyl group with potassium permanganate in warm t -butanol afforded the carboxylic acid that was converted to the corresponding carboxamide via,/ the acid chloride. [source] Synthesis of [14C]-imexonJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2005Bhumasamudram Jagadish Abstract A four-step synthesis of [14C]-imexon is described, starting from [14C]-phosgene. The overall yield is 27% and the specific activity is 55 mCi/mmol. Copyright © 2005 John Wiley & Sons, Ltd. [source] Synthesis of JTT-501 and its metabolite JTP-20604 labelled with 13CJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 7 2003A. Pignatti Abstract JTT-501 specifically labelled with 13C was obtained via a four-step synthesis at an isotopic enrichment level of 99% and in 14% overall chemical yield starting from 4-hydroxy-[ring-U- 13C6]benzaldehyde (3). The hydrogenation of [13C6]JTT-501 over Pd/C gave [13C6]JTP-20604 in 90% chemical yield. Copyright © 2003 John Wiley & Sons, Ltd. [source] Mass spectrometry of steroid glucuronide conjugates.JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2001-diol 3-, -steroid-, -steroid-17- O -, 17-glucuronides, 3-keto-, Electron impact fragmentation of 3-keto-4-en-, glucuronides Abstract The steroid glucuronide conjugates of 16,16,17-d3 -testosterone, epitestosterone, nandrolone (19-nortestosterone), 16,16,17-d3 -nortestosterone, methyltestosterone, metenolone, mesterolone, 5,-androstane-3,,17,-diol, 2,2,3,4,4-d5 -5,-androstane-3,,17,-diol, 19-nor-5,-androstane-3,,17,-diol, 2,2,4,4-d4 -19-nor-5,-androstane-3,,17,-diol and 1,-methyl-5,-androstane-3,/,,17,-diol were synthesized by means of the Koenigs,Knorr reaction. Selective 3- or 17- O -conjugation of bis-hydroxylated steroids was performed either by glucuronidation of the corresponding steroid ketole and subsequent reduction of the keto group or via a four-step synthesis starting from a mono-hydroxylated steroid including (a) protection of the hydroxy group, (b) reduction of the keto group, (c) conjugation reaction and (d) removal of protecting groups. The mass spectra and fragmentation patterns of all glucuronide conjugates were compared with those of the commercially available testosterone glucuronide and their characterization was performed by gas chromatography/mass spectrometry and nuclear magnetic resonance spectroscopy. For mass spectrometry the substances were derivatized to methyl esters followed by trimethylsilylation of hydroxy groups and to pertrimethylsilylated products using labelled and unlabelled trimethylsilylating agents. The resulting electron ionization mass spectra obtained by GC/MS quadrupole and ion trap instruments, full scan and selected reaction monitoring experiments are discussed, common and individual fragment ions are described and their origins are proposed. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||