An efficient approach to the synthesis of highly congested 9,10-dihydrophenanthrene-2,4-dicarbonitriles and their biological evaluation as antimicrobial agents.

An efficient and novel method for the synthesis in moderate to good yield (72%-84%) of a series of 3-amino-1-substituted-9,10-dihydrophenanthrene-2,4-dicarbonitriles 1-5 via one-pot multi-component reactions of aldehydes, malononitrile, 1-tetralone and ammonium acetate has been delineated. Cyclocondensation attempts of aminocyanophenanthrene derivatives 1, 2, 4 and 5 with acetic anhydride in the presence of conc. H2SO4 failed and instead the diacetylamino derivatives 10-13 were obtained. All prepared compounds were structurally elucidated by various spectroscopic methods and X-ray crystallography. N,N-diacetylamino-derivatives of phenanthrene have shown good antimicrobial activity.