title: The diastereoisomers methyl 5-(S)-[2-(R)/(S)-methoxycarbonyl)-2,3,4,5-tetrahydropyrrol-1-ylcarbonyl]-1-(4-methylphenyl)-4,5-dihydropyrazole-3-carboxylate.
abstract: The title diastereoisomers, methyl 5-(S)-[2-(S)-methoxycarbonyl)-2,3,4,5-tetrahydropyrrol-1-ylcarbonyl]-1-(4-methylphenyl)-4,5-dihydropyrazole-3-carboxylate and methyl 5-(S)-[2-(R)-methoxycarbonyl)-2,3,4,5-tetrahydropyrrol-1-ylcarbonyl]-1-(4-methylphenyl)-4,5-dihydropyrazole-3-carboxylate, both C(19)H(23)N(3)O(5), have been studied in two crystalline forms. The first form, methyl 5-(S)-[2-(S)-methoxycarbonyl)-2,3,4,5-tetrahydropyrrol-1-ylcarbonyl]-1-(4-methylphenyl)-4,5-dihydropyrazole-3-carboxylate--methyl 5-(S)-[2-(R)-methoxycarbonyl)-2,3,4,5-tetrahydropyrrol-1-ylcarbonyl]-1-(4-methylphenyl)-4,5-dihydropyrazole-3-carboxylate (1/1), 2(S),5(S)-C(19)H(23)N(3)O(5) x 2(R),5(S)-C(19)H(23)N(3)O(5), contains both S,S and S,R isomers, while the second, methyl 5-(S)-[2-(S)-methoxycarbonyl)-2,3,4,5-tetrahydropyrrol-1-ylcarbonyl]-1-(4-methylphenyl)-4,5-dihydropyrazole-3-carboxylate, 2(S),5(S)-C(19)H(23)N(3)O(5), is the pure S,S isomer. The S,S isomers in the two structures show very similar geometries, the maximum difference being about 15 on one torsion angle. The differences between the S,S and S,R isomers, apart from those due to the inversion of one chiral centre, are more remarkable, and are partially due to a possible rotational disorder of the 2-(methoxycarbonyl)tetrahydropyrrole group.
authors.affiliation: CNR-Centro per lo Studio delle Relazioni fra Struttura e Reattività Chimica, c/o Dipartimento di Chimica-Fisica ed Elettrochimica, Università degli Studi di Milano, Via Golgi 19, 20133 Milano, Italy. pila@csrsrc.mi.cnr.it
authors.forename: Tullio
authors.initials: T
authors.lastname: Pilati
authors.forename: Gianluigi
authors.initials: G
authors.lastname: Casalone