The Advances and Applications of Arynes and Their Precursors to Synthesize the Heterocyclic Compounds: A Review

Abstract

The aryne and its intermediates or their precursors are the most important compounds in organic synthesis for the purpose of arynes or benzyne insertion in many reactions. Arynes are among the first reactive intermediates known to organic chemists. Since their discovery, they have fascinated chemists from both theoretical and synthetic perspectives. These remarkable intermediates possess a wide reactivity profile, engaging in the different types of reactions especially in organic chemistry fields like nucleophilic addition reactions, pericyclic reactions, [4+2] and [3+2] cycloaddition reactions and transition metal-mediated/catalyzed reactions. This methodology would also be applicable for the synthesis of biologically and pharmaceutically active products such as isocoumarins, benzodiazepines and other important compounds in one pot reactions.

Unveiling the Bonding Scenario in Metal–Aryne Complexes with EDA-NOCV Analyses

“…One of such areas includes bonding of transition metals with arynes since arynes are undoubtedly extremely reactive species, even at very low temperatures. Out of aryne systems, benzyne (1,2-didehydrobenzene) is the most widely studied, whose transient existence was initially confirmed through pioneering investigations conducted by Wittig and Roberts in the 1950s. Benzyne’s unique reactivity arises from this strained triple bond (the most common representation of benzyne, Figure ), and the generation of benzyne involves the 1,2-elimination of leaving groups from corresponding precursor, leading to its versatile reactivity toward nucleophiles and electrophiles, facilitating the construction of complex organic compounds.…”

Effects of the Distance between Radical Sites on the Reactivities of Aromatic Biradicals

“…σ-Type carbon-centered aromatic biradicals, including the three benzynes (ortho-, meta-, and para-) and their analogues, have been studied for decades for their potential application in various fields, including organic synthesis and anticancer therapeutics. − Because of the difficulty in clean and simultaneous generation of two radical sites that are not adjacent to each other in solution, mass spectrometers have been used to study numerous gas-phase aromatic biradicals with a chemically inert charged site. ,, These biradicals are generated from protonated diiodo- or iodonitro precursors by collision-activated dissociation to homolytically cleave off iodo atoms and/or nitro groups. In most cases, the charged site has been demonstrated to influence reactions like a strongly electron-withdrawing substituent, without directly participating in the reactions …”