Replacement of primary amino groups by hydrogen via tetrahydrodibenzacridinium salts

Abstract

5,6,8,9-Tetrahydrodibenzo[c,h]xanthylium salts (13) react with amines to yield the corresponding tetrahydroacridinium salts (14) which are reduced by NaBH₄ to hexahydroacridines (15). The N-alkylhexahydroacridines undergo thermolysis at ca. 160 °C and the N-aryl analogues at > 250 °C to give alkanes and arenes. The N-alkyltetrahydroacridinium salts (14) and their 7-phenyl analogues (12) react at ca. 130 °C with 1,5-diazabicyclo[4.3.0]non-5-ene to give the corresponding alkanes in good yield.