Transition-Metal-Catalyzed Reactions Involving Arynes

Abstract

The plethora of transformations attainable by the transition-metal-catalyzed reactions of arynes has found immense contemporary interest in the scientific community. This review highlights the scope and importance of transition-metal-catalyzed aryne reactions in the field of synthetic organic chemistry reported to date. It covers transformations achieved by the combination of arynes and various transition metals, which provide a facile access to a biaryl motif, fused polycyclic aromatic compounds, different novel carbocycles, various heterocycles, and complex natural products.1 Introduction2 Insertion of Arynes3 Annulation of Arynes4 Cycloaddition of Arynes5 Multicomponent Reactions of Arynes6 Miscellaneous Reactions of Arynes7 Total Synthesis of Natural Products Using Arynes8 Conclusion

Ir-Catalyzed Cascade C–H Fusion of Aldoxime Ethers and Heteroarenes: Scope and Mechanisms

“…By utilizing arynes as the alkyne analogues, Zhu’s group reported a Pd-catalyzed annulation of benzophenone O -perfluorobenzoyl oximes with O -(trimethylsilyl)­aryl triflates to synthesize phenanthridines (Scheme a) . Nevertheless, due to the high reactivity of the aryne synthons, the scope of this reaction is limited. Moreover, O -(trimethylsilyl)­aryl triflates serving as aryne precursors need to be prepared in advance, and heteroarynes are difficult to synthesize.…”

Catalyst-Controlled Annulations of Strained Cyclic Allenes with π-Allylpalladium Complexes

“…In situ-generated strained intermediates that bear a functional group with a preferred linear geometry within a small ring have emerged as valuable synthetic building blocks. Arynes − and cyclic alkynes , (e.g., 1 – 3 , Figure A) have been most well-studied with applications spanning the synthesis of heterocycles, , ligands (such as XPhos), natural products, − agrochemicals, and organic materials. , A related class of strained intermediates discovered around the same time as arynes and cyclic alkynes is strained cyclic allenes, such as 1,2-cyclohexadiene ( 4 ). , The cumulated diene confined to a small ring leads to ∼30 kcal/mol of strain energy, making cyclic allenes well-suited for strain-promoted reactions. − However, these intermediates have received significantly less attention compared to arynes and cyclic alkynes despite possessing many attractive attributes that substantiate their value as building blocks for the synthesis of complex sp 3 -rich scaffolds. Recent studies of strained cyclic allenes have led to advances in cyclic allene generation protocols, − cycloaddition reactions, − metal-catalyzed processes, ,, trapping in a single-electron process, DNA-encoded library synthesis, and total synthesis …”

Total Synthesis of Phenanthroindolizidines Using Strained Azacyclic Alkynes

“…In the forward sense, the fragments would be coupled via a palladium-catalyzed Larock annulation . Metal-mediated transformations of strained alkynes are known − and provide powerful tools for constructing multiple bonds in efficient transformations. However, examples involving strained, azacyclic alkynes are less common, and metal-catalyzed reactions of piperidynes remain unknown.…”