Olefination with sulfonyl halides and esters – sulfur-based variant of the Horner-Wadsworth-Emmons reaction

Among carbonyl olefination reactions sulfur-based protocols play a prominent role, utilizing aryl and hetaryl sulfones in processes referred as ‘classical’ and ‘one-pot’ Julia olefinations. However, a related, but much less common method, which is based on the reactivity of sulfonyl halides and esters (sulfonates), features a different reaction mechanism. Accordingly, carbanions of the precursors add to aldehydes and ketones, cyclize to four membered ring intermediates and syn-fragment to alkenes, mimicking transformations of organic phosphonates (the Horner-Wadsworth-Emmons reaction). The presented mini-review compiles early reports from the 1990s with a series of recent articles, in which the ‘overlooked’ olefination method was systematically studied.