Synthesis, X-ray, DFT Studies and Antimicrobial Properties of New Quinolinylphosphonates

The phosphorus atom in hexamethyl phosphorus triamide 5 attacks the carbonyl function in 2-chloroquinoline-3-carbaldehyde 4a to give the bis-quinolinyl ethanone product 6. On the other hand, quinoline ring-attack proceeds by the same phosphorus reagent upon reaction with 2-chloroquinoline- 3-aldoxime 4b yielding phosphonate 7. Meanwhile, the reaction of the tris-aminophosphine reagent 5 with 2-chloroquinoline- 3-(p-chlorophenyl)imine 4c affords the respective α-aminophosphonate 8. Moreover, the attack by phosphine 5 on 2-chloroquinoline-3-imines 4d and 4e produces the respective cyclic azophosphole derivatives 9a and 9b. [(2-chloroquinolin-3-yl)methylidene]propane dinitrile 4f reacts with phosphine 5 to yield [(2-chloroquinolinen-3-yl) 2,2-dicyanoethyl]tetramethylphosphonic diamide 10. Structural elucidations for the new products were based on compatible analytical and spectroscopic data. Moreover, the structures assigned for compounds 7 and 9a were unambiguously confirmed by X-ray crystallographic measurements. Biological evaluations indicated that compounds 4a,c exhibit antibacterial potency against Gram-positive bacteria and 4a,c and 9a show activity against Candida albicans strain.