Stereoselective Synthesis of α-Fluoro Carboxylic Acids by Ireland-Claisen Rearrangement

Org Lett. 2023 Aug 25;25(33):6167-6171. doi: 10.1021/acs.orglett.3c01276. Epub 2023 Aug 17.

Abstract

Stereoselective synthesis of α-fluoro carboxylic acids by the Ireland-Claisen rearrangement can provide a straightforward approach to this class of compounds. We report a systematic investigation of base-dependent stereocontrol in the Ireland-Claisen rearrangement of α-fluoro esters. For substrates with various substitution patterns, the use of KN(SiMe3)2 in toluene afforded rearrangement products corresponding to the (Z)-enolate intermediate with a practically useful diastereoselectivity and yield. In contrast, lower yields and diastereoselectivity were consistently observed with the use of lithium diisopropylamide (LDA) in tetrahydrofuran (THF).