Extension of the 5-alkynyluridine side chain via C–C-bond formation in modified organometallic nucleosides using the Nicholas reaction

• Renata Kaczmarek,
• Dariusz Korczyński,
• James R. Green and
• Roman Dembinski

Beilstein J. Org. Chem. 2020, 16, 1–8, doi:10.3762/bjoc.16.1

• hexacarbonyl complexes; Nicholas reaction; nucleosides; propargyl cation; Introduction Nucleoside analogs are molecules of high pharmacological interest for the treatment of various conditions, especially cancer and viral diseases [1][2][3][4][5]. The substitution at C-5 of the uracil nucleobase provides a

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• 113.5 ppm, respectively. The sequence probably commences with pyridine-assisted conversion of propargylic alcohol 31 to the propargyl triflate, which looses triflate, forming propargyl cation 33. Since a triflone is formed rather than a triflate, reduction of the incoming nucleophile must have taken

• to the formation of pyridinium triflinate. It has also been reported that the triflinate anion can be generated from 2,6-lutidine/Tf2O [28] or Et3N/Tf2O [29]. Allenyl triflone 34 could be formed by attack of triflinate as S-nucleophile [30] at the chain carbon of propargyl cation 33. An alternative