Synthesis of Salts of 1,2,5,6- and 1,4,5,8-Naphthalenetetramine

1,2,5,6-Naphthalenetetramine (1a), its 1,4,5,8-isomer
(2a), and their salts are valuable precursors for synthesizing
nitrogen-containing arenes and other targets of interest. We describe
how salts of tetramines 1a and 2a can be
made from simple protected derivatives of 1,5-naphthalenediamine (2d) by sequences of regioselective dinitration, deprotection,
and reduction. Various shortcomings of previously reported syntheses
of tetramines 1a and 2a can thereby be avoided.
In addition, we report structural studies that may help clarify the
mechanism of nitration and resolve an earlier controversy about the
regioselectivity observed in nitrations of derivatives of 1,5-naphthalenediamine
(2d).