Norbert Krause

The ring‐opening Si‐fluorination of a variety of azasilole derivatives cyclo ‐1‐( i Pr 2 Si)−4‐X−C 6 H 3 −2‐CH 2 NR ( 4 : R=2,6‐ i Pr 2 C 6 H 3 , X=H; 4 a : R=2,4,6‐Me 3 C 6 H 2 , X=H; 9 : R=2,6‐ i Pr 2 C 6 H 3 , X= t BuMe 2 SiO; 10 : R=2,6‐ i Pr 2 C 6 H 3 , X=OH; 13 : R=2,6‐ i Pr 2 C 6 H 3 , X=HCCCH 2 O; 22 : R=2,6‐ i Pr 2 C 6 H 3 , X= t BuMe 2 SiCH 2 O) with different 19 F‐fluoride sources was studied, optimized and the experience gained was used in a translational approach to create a straightforward 18 F‐labelling protocol for the azasilole derivatives [ 18 F] 6 and [ 18 F] 14 . The latter constitutes a potential clickable Cyclo SiFA prosthetic group which might be used in PET tracer development using Cu‐catalysed triazole formation. Based on our findings, Cyclo SiFA has the potential to become a new entry into non‐canonical labelling methodologies for radioactive PET tracer development.

A transition metal‐free method for the cycloisomerization of propargylic amides to oxazoles was developed. The reaction utilizes in situ generated hydrogen chloride in hexafluoroisopropanol (HFIP). With the aid of Design of Experiments optimization a wide range of substrates was transformed into the desired oxazoles. The method allows product formation without side reactions eliminating the need for extensive work‐up and purification. magnified image