Abstract
<jats:p>Considering the growing demand for environmentally non-persistent perfluoro monomers due to their unique physicochemical diversity, herein we report a chloropentafluorosulfanylative radical cascade three-component coupling between a terminal aromatic alkyne, a Michael acceptor (an electron-deficient olefin), and gaseous pentafluorosulfanyl chloride, yielding perfluorosulfanyl enenitrile (or enoate). Mechanistically, an external radical initiator or photo-mediated generation of •SF5 radical via a homolytic cleavage of the S-Cl bond of SF5Cl underwent anti-Markovnikov addition to the terminal alkyne, leading to SF5-vinyl radical intermediate. Next, this fluorinated olefin radical sequentially coupled with the Michael acceptor, a second molecule of alkyne, and eventually abstracted a •Cl radical to yield the desired product. Different control experiments, isolation of the by-product, and detection of several intermediates provided evidence for a radical-mediated, electronically preferred sequential coupling mechanism. This protocol demonstrated 100% atom-economical fluoro-organic synthesis. The unique chemical reactivity and subsequent post-synthetic modifications evidence the synthetic importance of perfluorosulfanyl enenitriles (or enoates).</jats:p>