A new highly stereoselective monofluorination in benzylic position

DAST-promoted Beckmann rearrangement/intramolecular cyclization of acyclic ketoximes: access to 2-oxazolines, benzimidazoles and benzoxazoles

The first example of DAST-promoted Beckmann rearrangement/intramolecular cyclization of acyclic ketoximes is described, which affords 2-oxazolines, benzimidazoles and benzoxazoles.

A continuous-flow protocol for light-induced benzylic fluorinations

A continuous-flow protocol for the light-induced fluorination of benzylic compounds is presented. The procedure uses Selectfluor as the fluorine source and xanthone as an inexpensive and commercially available photoorganocatalyst. The flow photoreactor is based on transparent fluorinated ethylene propylene tubing and a household compact fluorescent lamp. The combination of xanthone with black-light irradiation results in very efficient fluorination. Good to excellent isolated yields were obtained for a variety of substrates bearing different functional groups applying residence times below 30 min.

The propargylic route as a short and versatile entry to optically active monofluorinated compounds

Using selected models and appropriate NMR techniques, it has been demonstrated that dehydroxyfluorination in the propargylic position can be highly regio- and stereoselective. The corresponding propargylic fluorides are very useful intermediates for short preparations of stereodefined unsaturated or polyunsaturated compounds with a single fluorine atom in allylic or propargylic position. This strategy offers good means for the synthesis of chiral, nonracemic monofluorinated analogues of natural products.

Synthesis of new optically active propargylic fluorides and application to the enantioselective synthesis of monofluorinated analogues of fatty acid metabolites

A new approach to obtain optically active unsaturated or polyunsaturated systems with a single fluorine atom in an allylic or propargylic position is reported. Central to this strategy is the high regio- and stereocontrol observed during the fluorination of propargylic alcohols allowing a short and efficient synthesis of 1. Further, simple functional group transformations gave the enals 2 and 3. These three key intermediates were used for the preparation of optically active monofluorinated analogues of fatty acid metabolites.