TY - JOUR
T1 - X-ray supramolecular structure, NMR spectroscopy and synthesis of 3-methyl-1-phenyl-1H-chromeno[4,3-c]pyrazol-4-ones formed by the unexpected cyclization of 3-[1-(phenylhydrazono)ethyl]-chromen-2-ones
AU - Padilla-Martinez, Itzia I.
AU - Flores-Larios, Irma Y.
AU - García-Baez, Efren V.
AU - Gonzalez, Jorge
AU - Cruz, Alejandro
AU - Martínez-Martinez, Francisco J.
PY - 2011/1
Y1 - 2011/1
N2 - The molecular structures of nine 3-methyl-1-phenyl-1H-chromeno[4,3-c] pyrazol-4-one isomers, obtained by the oxidative cyclization of the corresponding 1-phenylhydrazono chromen-2-ones with copper acetate as catalyst, are reported. The molecular and supramolecular structures of the 8-chloro, 8-bromo-and 8-nitro isomers 2b-d, were established by X-ray diffraction. The halogenated isomers 2b and 2c are isomorphs, they crystallize as a triclinic system, space group P-1 with two molecules in the asymmetric unit. Compound 2d crystallizes as a monoclinic system, space group P21/m with two molecules in the unit cell. The 1-phenyl ring [Cg(4)] is almost perpendicularly positioned to the chromene-pyrazole ring system. This conformation is in agreement with the anisotropic NMR shielding effect exerted by the phenyl ring over H-9 in solution. The supramolecular architecture is almost controlled by C-H···A (A = O, π) and face to face π-stacking interactions. The observed π-stacking trend between chromene and pyrazole rings is given by the overlapping between the best donor and acceptor rings in each compound.
AB - The molecular structures of nine 3-methyl-1-phenyl-1H-chromeno[4,3-c] pyrazol-4-one isomers, obtained by the oxidative cyclization of the corresponding 1-phenylhydrazono chromen-2-ones with copper acetate as catalyst, are reported. The molecular and supramolecular structures of the 8-chloro, 8-bromo-and 8-nitro isomers 2b-d, were established by X-ray diffraction. The halogenated isomers 2b and 2c are isomorphs, they crystallize as a triclinic system, space group P-1 with two molecules in the asymmetric unit. Compound 2d crystallizes as a monoclinic system, space group P21/m with two molecules in the unit cell. The 1-phenyl ring [Cg(4)] is almost perpendicularly positioned to the chromene-pyrazole ring system. This conformation is in agreement with the anisotropic NMR shielding effect exerted by the phenyl ring over H-9 in solution. The supramolecular architecture is almost controlled by C-H···A (A = O, π) and face to face π-stacking interactions. The observed π-stacking trend between chromene and pyrazole rings is given by the overlapping between the best donor and acceptor rings in each compound.
KW - Benzopyrano-arylhydrazone
KW - Benzopyrano-pyrazolone
KW - Oxidative cyclization
KW - Pi-stacking
UR - http://www.scopus.com/inward/record.url?scp=79251498333&partnerID=8YFLogxK
U2 - 10.3390/molecules16010915
DO - 10.3390/molecules16010915
M3 - Artículo
C2 - 21258298
AN - SCOPUS:79251498333
SN - 1420-3049
VL - 16
SP - 915
EP - 932
JO - Molecules
JF - Molecules
IS - 1
ER -