Ethynyl-SF<sub>4</sub>-Pyridines: Reagents for SF<sub>4</sub>-Alkynylation to Carbonyl Compounds
Kentaro Iwaki, Koki Maruno, Osamu Nagata, Norio Shibata
Abstract
The trans-tetrafluoro-λ6-sulfanyl (SF4) unit is medicinally attractive because of its high electronegativity, lipophilicity, and unique hypervalent structure. The trans-SF4 unit can characteristically connect two independent molecules linearly. However, there is no example of the use of this unit for medicinal chemistry due to difficulties in synthesis. We report the first synthesis of (ethynyl-trans-tetrafluoro-λ6-sulfanyl)pyridines (t-ethynyl-SF4-pyridines) and their use as versatile reagents for the first direct SF4-alkynylation to carbonyl compounds. The addition reaction of t-ethynyl-SF4-pyridines to the carbonyl group in the presence of MeLi smoothly afforded pyridine-SF4-propargylic tertiary and secondary alcohols in high yields.