Process for preparing 1,5-diaminonaphthalene derivative

A process for preparing a 1,5-diaminonaphthalene derivative comprising:

• (i) the first step comprising reacting an ortho-alkylnitrobenzene represented by formula (1):
• wherein R1 to R4, which may be the same or different, represent hydrogen, alkyl having 1 to 4 carbon atoms, aromatic hydrocarbon having 6 to 12 carbon atoms, or halogen;
• and R5 represents hydrogen, with a vinyl compound represented by formula (2):
• wherein R6 and R7, which may be the same or different, represent hydrogen, alkyl having 1 to 4 carbon atoms, or halogen;
• and X represents an electron withdrawing group, provided that R6 and R7 are mutually cis- or trans-configured, in the presence of a base, to produce an aromatic nitro compound represented by formula (3):
• wherein R1 to R7 are as defined in formulas (1) and (2);
• and X represents an electron withdrawing group, which may be the same as or different from X as defined in formula (2);
• (ii) the second step of cyclizing the aromatic nitro compound represented by formula (3) to produce a 5-nitro-1-tetralone derivative represented by formula (4):
• wherein R1 to R4 and R6 to R7 are as defined in formulas (1) and (2);
• and
• (iii) the third step comprising reacting the 5-nitro-1-tetralone derivative represented by formula (4) with an amine to provide an intermediate, which is then reduced and aromatized to produce the 1,5-diaminonaphthalene derivative represented by formula (5):
• wherein R1 to R4 and R6 to R7 are as defined in formulas (1) and (2).