Regioselective functionalisation of nitrobenzene and benzonitrile derivatives via nucleophilic aromatic substitution of hydrogen by phosphorus-stabilized carbanions |
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Authors: | Carmen M Andújar Sánchez |
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Institution: | Área de Química Orgánica, Universidad de Almería, Carretera de Sacramento, 04120 Almería, Spain |
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Abstract: | The synthesis of P-benzylic products by reaction of anions stabilised by N-phosphorylphosphazenyl, N-methoxycarbonylphosphazenyl, phosphine borane complex, and phosphine oxide groups by displacement of hydrogen of a variety of electron-deficient benzene derivatives is described. Lithium phosphazenes were the most suitable nucleophiles for the substitution of hydrogen in nitrobenzene and some ortho-, meta-, and para- substituted nitrobenzenes. Lithiated phosphine borane complexes produced efficiently the substitution of the hydrogen at the para position of a cyano group in cyanobenzenes, whereas the anion of ethyldiphenylphosphine oxide lead to complex mixtures with all electrophiles assayed. The method reported here represents a convenient alternative to the vicarious nucleophilic substitution for the synthesis of benzylic phosphorus derivatives using phosphorus-stabilised anions that do not bear a leaving group at the carbanionic centre. |
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Keywords: | Phosphazenes Phosphine-boron complexes Nucleophilic aromatic substitution Carbanions Cyano group |
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