Prins fluorination cyclisations: Preparation of 4-fluoro-pyran and -piperidine heterocycles.
The Prins reaction was investigated using BF₃.OEt₂ as a Lewis acid. It has been recently demonstrated, that if BF₃.OEt₂ is used in stoichiometric amounts then these reactions generate fluorinated products where the BF₃.OEt₂ contributes fluoride ion to quench the intermediate carbocations. In this study oxa- and aza-Prins reactions for the synthesis of 4-fluoro-pyrans and -piperidines were investigated. The products were obtained in good yields, but only with moderate diastereoselectivity. These Prins fluorination reactions can be accelerated under microwave conditions. The study extends the Prins fluorination methodology for the generation of the C-F bond in heterocycles.
Launay
Guillaume G
GG
School of Chemistry and Centre for Biomolecular Sciences, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, United Kingdom.
Slawin
Alexandra M Z
AM
O'Hagan
David
D