Stereoselective Enolboration of α-Trifluoro-methylpropionates

Significance

The introduction of fluorine into organic molecules can have a beneficial effect from a medicinal chemistry standpoint. The stereocontrolled crossed aldol reaction is a powerful synthetic tool; however, metal enolates of α-trifluoro­methylpropionates often undergo defluorination due to interaction of the metal with fluorine. A handful of procedures exist for the enolization of α-trifluoromethylcarbonyl compounds, for example, using titanium and a suitable base or via DIBAL-H reduction of alkenyl phosphates. The authors report on the highly anti-selective crossed aldol reaction of enolboronates of α-trifluoromethylpropionates with aldehydes and demonstrate its application to a fragment of 6-CF₃-dictyostatin.