The nucleophilicity of the amino group in the 6-th and 7-th positions of 1,4-naphthoquinone and the comparison with the activity of the amino group in the 2-nd position of 1,4-naphthoquinone have been investigated. Therefore, alkylation reactions were performed with alkyl iodides, acylation with acetate anhydride, and also interaction with sulfinyl chloride and sulfonyl chloride was carried out.
Using EtI or i-PrI in benzene, with the addition of Et3N alkylation of 2,3,6-trichloro-7-amino-1,4-naphthoquinone, 2-amino-3,6-dichloro-7-nitro-1,4-naphthoquinone and 2-N-morpholino-3-chloro-6-amino-7-nitro-1,4-naphthoquinone was carried out.
2-N-acyl derivatives acylation of the amino group of 7-amino-2,3,6-trichloro-1,4-naphthoquinone, 2-amino-3,6-dichloro-1,4-naphthoquinone, 2-N-morpholino-3-chloro-6-amino-7-nitro-1,4-naphthoquinone was carried out with acetic anhydride at room temperature. Synthesis of 1,4-naphthoquinones with sulphonylamides and sulfonylamides was carried out in a medium of benzene, with addition of Et3N to give 2-N-sulfinyl (sulfonyl) amide derivatives, 6-N-sulfinyl (sulfonyl) amide derivatives and 7-N-sulfinyl (sulfonyl) amide derivative. Alkylation of diamines: 2,7-diamino-3,6-dichloro-1,4-naphthoquinone and 2-N-morpholino-3-chloro-6,7-diamino-1,4-naphthoquinone, yielded 2,7-dialkyl derivatives, which indicates a lower reactivity of amino groups than in the 6.7-dialkyl derivatives.
Products of diacylation are formed by the way of acylating diamines 2,7-diamino-2,6-dichloro-1,4-naphthoquinone and 2-N-morpholino-3-chloro-6,7-diamino-1,4-naphthoquinone
As a result of our research, we have seen that under the same conditions of reaction, the position of the amino group has a significant influence on the yield of the final product. In the presence of an amino group in the molecule of substituted 1,4-naphthoquinone there is displacement of electronic density in the direction of the naphthoquinone cycle with an appropriate change of charge on the carbon atoms in a certain position. 7-Amino substituted derivatives give yields greater than 75%, 6-amino substituted - 60-70%, and 2-amino-substituted compounds - 40-50% respectively.
It was established that due to the displacement of the electron density from the amino group in the 2-nd position towards the quinone cycle, it exhibits very weak nucleophilic properties.
For synthesized substances, a virtual biological screening was conducted using the PASS online program, which demonstrated the feasibility of further studies of the biological activity of 2,6,7-substituted 1,4-naphthoquinones to find new drugs with high pharmacological effects and low toxicity.
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