Synthesis and Antifungal Activity of 1-Aryl-3-phenethylamino-1-propanone Hydrochlorides and 3-Aroyl-4-aryl-1-phenethyl-4-piperidinols

Mono-Mannich bases, 1-aryl-3-phenethylamino-1-propanone hydrochlorides, 1a, 2a, 3a, 4a, 3a, 6a, 7a, 8a, 9a, and semi-cyclic mono-Mannich bases, 3-aroyl-4-aryl-1-phenethyl-4-piperidinols, 1b, 2b, 3b, 4b, 5b, 6b, 7b, 8b, 9b, were synthesized by a non-classical Mannich reaction. The aryl part was: C(6)H(5) for 1a, 1b; 4-CH(3)C(6)H(4) for 2a, 2b; 4-CH(3)OC(6)H(4) for 3a, 3b; 4-ClC(6)H(4) for 4a, 4b; 4-FC(6)H(4) for 5a, 5b; 4-BrC(6)H(4) for 6a, 6b; 2,4-(Cl)(2)C(6)H(3) for 7a, 7b; 4-NO(2)C(6)H(4) for 8a, 8b; and C(4)H(3)S(2-yl) i.e., 2-thienyl for 9a, 9b. Piperidinol compounds 2b, 3b, 4h, 5b, 7b, 8b, and 9b are reported here for the first time. The synthesized compounds were tested against seven types of plant pathogenic fungi and three types of human pathogenic fungi using the agar dilution assay. Itraconazole was tested against Candida parapsilosis as the reference compound, while Nystatin was tested as the reference compound against the other fungi. Compounds 1a, 1b, 2a, 4a, 4b, 5a, 5b, 6a, 7a, 8a, 9a, and 9b can be selected as model compounds to develop new antifungal agents against the human pathogen Microsporum canis. Compounds 8a and 8b, which had a similar antifungal activity compared with the reference compound Nystatin against the plant pathogen Aspergillus flavus, can serve as model compounds to develop new antifungal agents to solve agricultural problems.