Effects of substituents on the rates of addition of 2-phenylpropionitrile carbanion to nitroarenes

Mieczysław Mąkosza,Daniel Sulikowski,Maciej Gola,Hiriyakkanavar Ila

doi:10.3998/ark.5550190.0010.619

Mieczysław Mąkosza, Daniel Sulikowski + Show 2 more

Open Access

https://doi.org/10.3998/ark.5550190.0010.619

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Abstract

The effects of substituents located ortho- and meta- to the nitro group in nitroarenes on the rates of addition of 2-phenylpropionitrile carbanion at the para- position were determined using oxidative nucleophilic substitution of hydrogen as the model process via competitive experiments. It was shown that the observed overall effects result from the superposition of primary and secondary electronic and steric effects.

Highlights

Nucleophilic substitution of hydrogen in electron-deficient arenes is a well established, versatile tool in organic synthesis.[1,4] The key step of this process is the addition of nucleophilic agents to these arenes to produce σH- adducts that are subsequently converted into the final products
The general character and value for synthesis of the nucleophilic substitution of hydrogen is due to the fact that the addition of nucleophiles in positions occupied with hydrogen leading to σH adducts proceeds faster than in those occupied by other substituents such as halogens
In this paper we present the results of similar studies of the effects of substituents on the rate of nucleophilic addition to nitroarenes of the model carbanion of 2-phenylpropionitrile 1 via ONSH reaction

Summary

Introduction

Nucleophilic substitution of hydrogen in electron-deficient arenes is a well established, versatile tool in organic synthesis.[1,4] The key step of this process is the addition of nucleophilic agents to these arenes to produce σH- adducts that are subsequently converted into the final products. We have shown that the VNS reaction can be used as an efficient tool for determination of the electrophilic activities of nitroarenes, the effect of substituents on rates of addition of carbanions to electron–deficient aromatic rings.[11,12] the effects of substituents on rates of nucleophilic substitution of halogens and other nucleofugal groups, the SNAr reaction, in substituted nitroarenes was thoroughly studied 2,13 the resulting data do not reflect the true electrophilic activities of the arenes. As a result of this, we have used the VNS reaction and determined relative rates of the nucleophilic addition in the position occupied by hydrogen in nitroarenes for the model carbanions of chloromethyl phenyl sulfone in competitive experiments under conditions that assure fast elimination of HCl from the σH- adducts.[11,12] Under such conditions the ratio of the products of the VNS reaction of competing nitroarenes reflects the ratio of the rate constants of the addition, and the electrophilic activity of arenes

Results and Discussion

F CN CF3 COOMe

Conclusions