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Full-Text Articles in Physical Sciences and Mathematics
Isolation And Identification Of A New Acetildenafil Analogue Used To Adulterate A Dietary Supplement: Dimethylacetildenafil, Ali̇ Hakan Göker, Maksut Coşkun, Mehmet Alp
Isolation And Identification Of A New Acetildenafil Analogue Used To Adulterate A Dietary Supplement: Dimethylacetildenafil, Ali̇ Hakan Göker, Maksut Coşkun, Mehmet Alp
Turkish Journal of Chemistry
A new sildenafil analogue was found to have been added illegally to a dietary supplement marketed for the enhancement of sexual function. The structure was determined as 5-(2-ethoxy-5- {[4-(3,5-dimethyl)piperazin-1-yl]-acetyl}phenyl)-1,6-dihydro-1-methyl-3- propyl-7H-pyrazolo [4,3-d]pyrimidin-7-one. Owing to the inclusion of a dimethyl group in acetildenafil, the detected compound was called dimethylacetildenafil. The sample was purified with column chromatography. The IR, LC/MS (ESI), and completely assigned NMR data of dimethylacetildenafil are reported for the first time. The structure was compared with that of acetildenafil and the results showed that the ethyl substitution at the 4-position of the piperazine ring had been replaced by a 3,5-dimethyl …
Effect Of Various Substituents On Intramolecular 1,1-Vinylboration, Synthesis Of 1-Silacyclobutene Derivatives, Ezzat Khan, Bernd Wrackmeyer
Effect Of Various Substituents On Intramolecular 1,1-Vinylboration, Synthesis Of 1-Silacyclobutene Derivatives, Ezzat Khan, Bernd Wrackmeyer
Turkish Journal of Chemistry
The reaction of 1-boryl-1-alkenyl chlorosilane derivatives with alkynyllithium reagents [Li-C\equiv C-R^3 (R^3~=~Ph, SiMe_3)] at low temperature (--78 °C) affords alkenyl(alkyn-1-yl)silanes. These compounds are precursors of 1-silacyclobutene derivatives, which are formed via intramolecular 1,1-vinylboration. This reaction works for various groups at silicon (R^1/R^2: R^1 = H, Me, Ph; R^2 = Me, Ph) and at the C=C and C\equiv C units (R/R^3: R = ^nBu, Ph; R^3 = ^nBu, Ph, SiMe_3). The conversion into 1-silacyclobutene derivatives is incomplete only in the case of R^3 = SiMe_3. The reactions were monitored by NMR spectroscopy in order to elucidate the reaction mechanism, and the …