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Abstract A dearomatization-dislocation-coupling cascade rapidly transforms aromatic isocyanides into highly functionalized cyclohexadienes. The facile cascade installs an exceptional degree of molecular complexity: three carbon-carbon bonds, two quaternary stereocenters, and three orthogonal functionalities, a cyclohexadiene, a nitrile, and an isocyanide. The tolerance of arylisocyanides makes the method among the mildest dearomatizations ever reported, typically occurring within minutes at −78 °C. Experimental and computational analyses implicate an electron transfer-initiated mechanism involving an unprecedented isocyanide rearrangement followed by radical-radical anion coupling. The dearomatization is fast, proceeds via a complex cascade mechanism supported by experimental and computational insight, and provides complex, synthetically valuable cyclohexadienes. 

Isocyanoalkenes are a largely underexplored subset of isocyanides whose natural occurrence, synthesis, and reactivity are elucidated in this review. The discussion begins with an overview of the biosynthesis and natural occurrence, which provides a valuable context for the synthetic approaches to these unusual π-substituted alkenes. Building on this foundation, the review explores the characteristic reactivity of isocyanoalkenes, which is shaped by the strong electron-withdrawing nature of the isocyanide group and an almost complete lack of π-conjugation. Two primary modes of reactivity are highlighted: conjugate additions – especially in systems containing additional electron-withdrawing substituents – and radical additions to the isocyanide, often followed by annulation via iminyl radical intermediates. Special attention is given to two particularly versatile isocyanoalkenes – β-dimethylaminoisocyanoacetates and β-bromoisocyanoacetates – which readily undergo nucleophilic addition–elimination–cyclization sequences to efficiently assemble nitrogen-containing heterocycles. Overall, this review underscores the synthetic potential of isocyanoalkenes and highlights their emerging value in the construction of diverse heterocyclic scaffolds. 

Metalated isocyanides are highly versatile organometallics. Central to the reactivity of metalated isocyanides is the presence of two orthogonally reactive carbons, a highly nucleophilic “carbanion” inductively stabilized by a carbene-like isocyanide carbon. The two reactivities are harnessed in the attack of metalated isocyanides on π-electrophiles where an initial nucleophilic attack leads to an electron pair that cyclizes onto the terminal isocyanide carbon in a rapid route to diverse, nitrogenous heterocycles. Harnessing the potent nucleophilicity of metalated isocyanides while preventing electrophilic attack on the terminal isocyanide carbon has largely been driven by empirical heuristics. This review provides a foundational understanding by surveying the formation, structure, and properties of metalated isocyanides. The focus on the interplay between the structure and reactivity of metalated isocyanides is anticipated to facilitate the development and deployment of these exceptional nucleophiles in complex bond constructions.