Cycloaddition Initiated by Ynolates: High-Energy Dianion Equivalents as a Molecular Glue

Abstract In this paper, ynolate-initiated cycloaddition (annulation) to form a range of carbocycles and heterocycles is described. Ynolates consist of a ketene anion equivalent, which contains both nucleophilic and electrophilic moieties, and a carbodianion equivalent that achieves double addition. Hence, in addition to the usual [n+2] cycloaddition, ynolates can perform formal [n+1]-type annulations. Their high-energy performance has been demonstrated by their triple addition to arynes to generate triptycenes, in which the C–C triple bond of ynolates is cleaved. The synthetic applications of these methods, including natural products synthesis, are also described. 1 Introduction 2 Preparation of Ynolates 2.1 Double Lithiation 2.2 Flow Synthesis 2.3 Double Deprotonation 3 [2+2] Cycloaddition to C=O Bond 3.1 To Aldehydes and Ketones 3.2 Sequential Cycloaddition 4 [2+2] Cycloaddition to Imino Groups