Synlett 2022; 33(06): 531-545
DOI: 10.1055/s-0040-1719857
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Cycloaddition Initiated by Ynolates: High-Energy Dianion Equivalents as a Molecular Glue

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Financial support was provided by the Japan Society for the Promotion of Science (JSPS KAKENHI; grant no. JP18H02557, JP18H04418, JP18H04624, JP20H04780, JP20K21198, and JP20K15283), NAGASE Science Technology Foundation (M.S.), Asahi Glass Foundation (T.I.), Qdai-jump Research Program Wakaba Challenge at Kyushu University (T.I.), and the IRCCS Fusion Emergent Research Program (T.I.).


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



Publication History

Received: 21 October 2021

Accepted after revision: 28 October 2021

Article published online:
22 November 2021

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