Synthesis of 3-R-1,5-DINITRO-3-AZABICYCLO[3.3.1]NON-7-EN-6-IMINES Based on 2,4-Dinitroaniline

Abstract

We have synthesized new derivatives of 3-azabicyclo[3.3.1]nonane by Mannich condensation of the hydride σ-adduct of 2,4-dinitroaniline with formaldehyde and primary amines. The synthesis is carried out in two stages. In the first stage, the action of potassium tetrahydroborate (KBH4) on a solution of 2,4-dinitroaniline resulted in the reduction of the C=C bond of the aromatic ring with the formation of a two-charged hydride diadduct. The obtained diadduct without isolation from the solution and under ice cooling was introduced into the Mannich condensation reaction with formaldehyde and primary amine solution. When the reaction mixture is acidified with dilute phosphoric acid to pH 4÷5, the target products are crystallized. After recrystallization from acetone, the yield of target products, depending on the substituent at the nitrogen atom, was 65–70%. This method of obtaining is characterized by relative simplicity, the availability of reagents that makes it possible to carry out reaction under a mild acidic condition to 3-azabicyclo[3.3.1]nonane derivatives containing nitro groups that are promising from the point of view of further functionalization. The structure of the obtained compounds was proved by IR, 1H-, 13C-, two-dimensional correlation NMR spectroscopy, as well as high-resolution mass spectrometry (HRMS) data.