SOLID-STATE STRUCTURE DETERMINATION AND SOLUTION-STATE NMR CHARACTERIZATION OF THE (2R,4R)/(2S,4S)-DIASTEREOMERS AND (2R,4S)/(2S,4R)-DIASTEREOMERS OF THE AGRICULTURAL FUNGICIDE PROPICONAZOLE, THE (2R,4S)/(2S,4R)-SYMMETRICAL TRIAZOLE CONSTITUTIONAL ISOMER, AND A DITRIAZOLE ANALOG

Single-crystal X-ray diffraction analysis was used to determine the structure of a racemic diastereomer of the agricultural fungicide propiconazole [1-(2-(2,4-dichlorophenyl)-4-n-propyl-1,3-dioxolane-2-yl-methyl)-1-H-1,2,4-triazole] and of two by-products (a symmetrical 1,3,4-triazole racemic-constitutional isomer and a propiconazole ditriazole analogue). All three crystalline racemic-diastereomers had (2R,4S)/(2S,4R)-stereochemistry in which the n-propyl group was observed in a trans-to-phenyl disposition. Propiconazole (2R,4S)/(2S,4R)-diastereomer gives crystals belonging to the monoclinic space group P2(/)a, and, at 293 K, a = 8.1192(3), b = 18.9769(6), c = 10.7137(4) Angstrom, beta = 99.765(3)degrees, V = 1626.8(1) Angstrom(3), Z = 4, R(F) = 0.060, and R(w)(F) = 0.058. The constitutional isomer by-product (2R,4S)/(2S,4R)-1-(2-(2,4-dichlorophenyl)-4-n-propyl-1 ,3-dioxolane-2-yl-methyl)-1-H-1,3,4-triazole gives crystals belonging to the monoclinic space group P2(1)/n, and, at 293 K, a = 11.1763(6), b = 10.7716(4), c = 14.5804(8) Angstrom, beta = 107.445(4)degrees, V = 1674.6(1) Angstrom(3), Z = 4, R(F) = 0.043, and R(w)(F) = 0.043. The ditriazole by-product (2R,4S)/(2S,4R)-1-(2-(2-chloro-4-(1,2,4-trizaole-1-yl)phenyl)-4-n-propyl-1,3-dioxolane-2-yl-methyl)-1-H-1,2,4-triazole gives crystals belonging to the triclinic space group P $($) over bar$$ 1, and, at 193 K, a = 5.3329(8), b = 8.3738(7), c = 20.240(2) Angstrom, alpha = 84.213(6)degrees, beta = 87.20(1)degrees, gamma = 86.23(1)degrees, V = 896.5(2) Angstrom(3), Z = 2, R(F) = 0.046, and R(w)(F) = 0.051. The presence of both propiconazole (2R,4S)- and (2S,4R)-enantiomers enables the formation Of a crystalline racemic modification, while the diastereomeric propiconazole (2R,4R)- and (2S,4S)-enantiomers are viscous oils. In the absence of its enantiomorphic partner, the propiconazole (2R,4S)- or (2S,4R)-enantiomers remain as viscous oils rather than form chiral crystals.