One‐Pot l‐Proline‐Mediated Stereoselective α‐C(sp2)–H Fluorination of α,β‐Unsaturated Aldehydes through Methoxyfluorination–Elimination

Abstract

A one‐pot, two‐step l‐proline‐mediated stereoselective α‐C(sp2)–H fluorination of α,β‐unsaturated aldehydes towards their corresponding (Z)‐α‐fluoro‐α,β‐unsaturated aldehydes has been developed. The first step utilises Selectfluor as a fluorinating agent in CH3NO2/MeOH forming (Z)‐α‐fluoro‐α,β‐unsaturated aldehydes and their corresponding dimethyl acetals through methoxyfluorination‐elimination. In the second step, water is added to promote the hydrolytic cleavage of the dimethyl acetals. The obtained (Z)‐α‐fluoro‐α,β‐unsaturated aldehydes were smoothly reduced to the corresponding alcohols by using NaBH4.