Synlett 2004(6): 955-958  
DOI: 10.1055/s-2004-820043
LETTER
© Georg Thieme Verlag Stuttgart · New York

A New Method for the Selective Amination of 1,3- and 1,4-Dinitrobenzenes and Protected Nitroanilines Leading to Polyfunctional 1,3- and 1,4-Disubstituted Anilines

Ioannis Sapountzis, Paul Knochel*
Department Chemie, Ludwig Maximilians Universität, Butenandtstrasse 5-13, 81377 München, Germany
Fax: +49(89)218077679; e-Mail: knoch@cup.uni-muenchen.de;
Further Information

Publication History

Received 11 December 2003
Publication Date:
25 March 2004 (online)

Abstract

The addition of functionalized arylmagnesium reagents to dinitrobenzenes and protected nitroanilines at -20 °C in THF ­furnishes after a reductive workup polyfunctional diarylamines in 47-92% yield.

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Typical Procedure: Preparation of ethyl 4-(3-nitro-phenylamino)benzoate (1d): In a dry and argon flushed 25 mL flask, equipped with a magnetic stirrer and a septum, ethyl 4-iodobenzoate (952 mg, 3.45 mmol) was dissolved in dry THF (8 mL), cooled to -20 °C and i-PrMgCl (3.6 mmol, 0.85 M in THF) was added dropwise. The I/Mg-exchange was complete after 30 min (as indicated by GC analysis of reaction aliquots) and 1,3-nitrobenzene (252 mg, 1.5 mmol) was added. After 2 h of stirring at -20 °C, the reaction mixture was quenched with EtOH (2 mL) and FeCl2 (378 mg, 3 mmol) and NaBH4 (57 mg, 1.5 mmol) were added. After 2 h stirring at r.t., the reaction mixture was poured onto brine (25 mL). The aqueous phase was extracted with Et2O (3 × 40 mL) and the organic fractions were washed with 2 M NaOH (30 mL), brine (30 mL), dried (Na2SO4) and concentrated in vacuo. Flash chromatography purification on silica gel (pentane/Et2O = 4:1) furnished 1d as red crystals (245 mg, 55% yield).