N-tert-butoxycarbonyl-N-substituted hydrazines in S(N)Ar displacements. Synthetic pathways to N-1-substituted anthrapyrazoles, aza-anthrapyrazoles and aza-benzothiopyranoindazoles

Article abstract of DOI:10.1002/jhet.5570370108

The synthesis of several N-tert-butoxycarbonyl(Boc)-protected-N- substituted hydrazines has been accomplished. The use of these protected hydrazines in S(N)Ar substitutions leads to products in which the most nucleophilic nitrogen displaces the leaving group. Treatment of these compounds with trifluoroacetic acid readily removes the Boc-protecting group and the intermediates readily undergo cyclizations to yield N-1-substituted aza-benzothiopyranoindazoles, anthrapyrazoles and aza-anthrapyrazoles. Side chain buildup was employed in the synthesis of several aza-anthrapyrazoles.