Recent advances in diverse reactions of γ-bromocrotonates and their derived allyl sulfonium salts

γ-Bromocrotonates and their derived allyl sulfonium salts serve as versatile synthons because they incorporate both an electron-withdrawing leaving group (bromine atom or sulfonium salt group) and a Michael acceptor (α,β-unsaturated ester group). This combination allows for the generation of various intermediates, leading to a wide range of subsequent transformations. Consequently, these synthons have garnered considerable attention, prompting the development of diverse methodologies and strategies for efficiently constructing functionalized organic molecules. In this review, we systematically summarize and elaborate on recent advances in diverse reactions of such versatile synthons. The discussed reactions are categorized according to γ-bromocrotonates and their derived allyl sulfonium salts acting as C1 synthons, C2 synthons, and C3 synthons, respectively, and provide detailed mechanistic insights. Additionally, this review highlights current challenges and future prospects for research in this field.