Commercially available CF 2 Br 2 has been used as a convenient source for the rapid and reliable incorporation of the gem-difluorovinyl motif into an allene framework via an Nheterocyclic carbene catalyzed difluoroolefination of 1,3-enynes. The reaction proceeds through a cascade three-component radical relay/elimination process. This protocol is distinguished by its mild conditions, readily accessible starting materials, wide substrate scope, and ease of late-stage functionalization, thus unlocking an untraditional strategy to construct a new class of functionalized gem-difluorovinyl allenes.O rganic backbones bearing the terminal gem-difluorovinyl (CF 2 �C) moiety are frequently found in the field of pharmaceuticals, agrochemicals, functional materials, and life science (Scheme 1a). 1 In particular, gem-difluoroalkenes are regarded as the ideal carbonyl bioisostere, mimicking the reactivity and property of the carbonyl group to improve bioactivity, metabolic stability, and target specificity in drug design. 2 Moreover, gem-difluoroalkenes are valuable building blocks in synthetic chemistry because they can be conveniently converted into diversely fluorinated compounds. 3 Likewise, the allene motif represents a privileged structure in numerous natural products and pharmacological agents. Given the importance of both gem-difluoroalkenes and allenes, the combination of these two scaffolds in one molecule seems to be a promising "hybrid pharmacophore" strategy in drug discovery. However, to the best of our knowledge, there is no approach to synthesize gem-difluorovinyl allenes.In recent years, great efforts have been devoted to developing new methods for the synthesis of functionalized gem-difluoroalkenes. 4 Traditional methods mainly focus on three different strategies (Scheme 1b): (1) difluoroolefination of alkyl halides, carbonyl, or diazo compounds; 5 (2) transitionmetal (TM)-catalyzed cross-coupling reaction of gem-difluorovinyl tosylate; 6 (3) defluorinative functionalization of αtrifluoromethyl alkenes 7 typically through defluorinative nucleophilic substitution, 8 TM-catalyzed defluorinative coupling reaction, 9 and photoredox-catalyzed or electrochemically promoted radical addition. 5g,10 Despite the impressive progress, the development of simple and more environmental benign metal-free methods for the synthesis of structurally diverse gem-difluoroalkenes from readily accessible starting materials is still in high demand. In this context, the pursuit of

An unprecedented organocatalytic asymmetric construction of novel six-membered carbocycle fused uracils has been demonstrated by the reaction of the remotely enolizable 6-methyluracil-5-carbaldehydes with 2-bromoenals. The reaction involves an N-heterocyclic carbene-catalyzed formal [4 + 2] annulation of o-quinodimethane (oQDM) dienolates with α,β-unsaturated acylazoliums, followed by a cascade lactone formation/decarboxylation process. This protocol unlocks a new platform to access enantioenriched carbocycle-fused uracils.

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Together with NCS, the catalyst showed a good activity in acetalization of aldehydes and alcohols. It could be recovered from the reaction mixture by fluorous solid-phase extraction (F-SPE) with excellent purity for direct reuse.