Exploration toward the synthesis of aliphatic SF5-containing compounds using the Kolbe reaction

The preparation of aliphatic SF5-compounds (i.e., RCH2CH2SF5 where R is a functionalized alkyl chain) using a Kolbe-based reaction was explored. In this electrochemical approach, 2-(pentafluoro-lambda 6-sulfanyl)acetic acid, used as the "SF5CH2" source, is reacted with an aliphatic carboxylic acid. A total of 9 examples of unsymmetrical coupling between 2-(pentafluoro-lambda 6-sulfanyl)acetic acid and a range of aliphatic carboxylic acid was achieved with NMR yields ranging from 15% to 66% (up to 62% isolated yield). Even if the method leads to modest yields, it represents one of the very few strategies to rapidly access aliphatic SF5-containing compounds.