Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Medicine and Health Sciences
Concise Synthesis Of Α-Substituted 2-Benzofuranmethamines And Other 2-Subsituted Benzofurans Via Α-Substituted 2-Benzofuranmethyl Carbocation Intermediates, Nikhom Wongsa, Ubonta Sommart, Thunwadee Ritthiwigrom, Arife Yazici, Somdej Kanokmedhakul, Kwanjai Kanokmedhakul, Anthony C. Willis, Stephen G. Pyne
Concise Synthesis Of Α-Substituted 2-Benzofuranmethamines And Other 2-Subsituted Benzofurans Via Α-Substituted 2-Benzofuranmethyl Carbocation Intermediates, Nikhom Wongsa, Ubonta Sommart, Thunwadee Ritthiwigrom, Arife Yazici, Somdej Kanokmedhakul, Kwanjai Kanokmedhakul, Anthony C. Willis, Stephen G. Pyne
Faculty of Science, Medicine and Health - Papers: part A
Propargyl amines 4, where R3 is aryl, undergo 5-exo-dig cyclization reactions under relatively mild conditions (AgNO3, DMF, 60 °C, 1 h) to give 3-amino-2,3-dihydro-2-arylmethylidenebenzofurans 5 (R3 = aryl). In contrast, substrates where R3 is alkyl undergo competing 6-endo-dig and 5-exo-dig cyclization processes. The hydroxymethyl substrate 4 (R3 = CH2OH), however, was smoothly converted to its corresponding 5-exo-dig cyclization product 5, likely due to the assistance of the primary hydroxyl group in the 5-exo-dig cyclization process by silver cation coordination. Under more enforcing conditions (AgNO3, DMF, 100 °C, 18 h), the initially formed products 5 undergo a 1,3-allylic rearrangement to their …
Interlaboratory Study For Coral Sr/Ca And Other Element/Ca Ratio Measurements, Ed C. Hathorne, Alex Gagnon, Thomas Felis, Jess Adkins, Ryuji Asami, Wim Boer, Nicolas Caillon, David Case, Kim M. Cobb, Eric Douville, Peter Demenocal, Anton Eisenhauer, Dieter Garbe-Schonberg, Walter Geibert, Steven Goldstein, Konrad Hughen, Mayuri Inoue, Hodaka Kawahata, Martin Kolling, Florence L. Cornec, Braddock K. Linsley, Helen V. Mcgregor, Paolo Montagna, Intan S. Nurhati, Terrence M. Quinn, Jacek Raddatz, Helene Rebaubier, Laura Robinson, Aleksey Sadekov, Robert Sherrell, Dan Sinclair, Alexander W. Tudhope, Gangjian Wei, Henri Wong, Henry C. Wu, Chen-Feng You
Interlaboratory Study For Coral Sr/Ca And Other Element/Ca Ratio Measurements, Ed C. Hathorne, Alex Gagnon, Thomas Felis, Jess Adkins, Ryuji Asami, Wim Boer, Nicolas Caillon, David Case, Kim M. Cobb, Eric Douville, Peter Demenocal, Anton Eisenhauer, Dieter Garbe-Schonberg, Walter Geibert, Steven Goldstein, Konrad Hughen, Mayuri Inoue, Hodaka Kawahata, Martin Kolling, Florence L. Cornec, Braddock K. Linsley, Helen V. Mcgregor, Paolo Montagna, Intan S. Nurhati, Terrence M. Quinn, Jacek Raddatz, Helene Rebaubier, Laura Robinson, Aleksey Sadekov, Robert Sherrell, Dan Sinclair, Alexander W. Tudhope, Gangjian Wei, Henri Wong, Henry C. Wu, Chen-Feng You
Faculty of Science, Medicine and Health - Papers: part A
The Sr/Ca ratio of coral aragonite is used to reconstruct past sea surface temperature (SST). Twenty-one laboratories took part in an interlaboratory study of coral Sr/Ca measurements. Results show interlaboratory bias can be significant, and in the extreme case could result in a range in SST estimates of 7°C. However, most of the data fall within a narrower range and the Porites coral reference material JCp-1 is now characterized well enough to have a certified Sr/Ca value of 8.838 mmol/mol with an expanded uncertainty of 0.089 mmol/mol following International Association of Geoanalysts (IAG) guidelines. This uncertainty, at the 95% confidence …