Synthesis 2023; 55(02): 354-358
DOI: 10.1055/s-0041-1737327
paper
Special Issue dedicated to Prof. Alain Krief

Elucidation of the Nucleophilic Potential of Diazocyclopentadiene

Manfred Hartnagel
,
Armin R. Ofial
,
Herbert Mayr
Financial support of this work by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie is gratefully acknowledged.


Dedicated to Professor Alain Krief on the occasion of his 80th birthday

Abstract

Diazocyclopentadiene reacts with benzhydrylium ions (Ar2CH+) to give 2,5-dibenzhydryl-substituted diazocyclopentadienes. The kinetics have been determined photometrically in dichloromethane under pseudo-first-order conditions using diazocyclopentadiene in excess. Plots of the second-order rate constants (log k 2) versus the electrophilicity parameters E of the benzhydrylium ions gave the nucleo­philicity parameter N = 4.84 and susceptibility s N = 1.06 for diazo­cyclopentadiene according to the correlation log k(20 °C) = s N(E + N). Diazocyclopentadiene thus has a similar nucleophilic reactivity as pyrrole. Previously reported electrophilic substitutions of diazocyclopentadiene are rationalized by these parameters and new reaction possibilities are predicted.

Supporting Information



Publication History

Received: 12 November 2021

Accepted: 17 November 2021

Article published online:
05 January 2022

© 2022. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany