title: Structural comparison of 1 beta-methylcarbapenem, carbapenem and penem: NMR studies and theoretical calculations.
abstract: Structural comparisons of meropenem (1), desmethyl meropenem (2) and the penem analogue (3) which contain the same side chains at both C-2 and C-6 were performed using 1H NMR measurements together with 3-21G* level of ab initio MO and molecular mechanics calculations. The ab initio MO calculations reproduced the skeletons of these strained beta-lactam rings in good agreement with the crystallographic data. 1H NMR measurements in aqueous solution together with molecular modeling studies indicated that there were conformational differences of the C-2 and C-6 side chains in this series of compounds. These observations suggested that the conformational differences could affect their biological activities.
authors.affiliation: Research Center, Sumitomo Pharmaceuticals Co., Ltd., Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Nishimura
authors.forename: J
authors.initials: J
authors.lastname: Igarashi
authors.forename: A
authors.initials: A
authors.lastname: Sasaki
authors.forename: M
authors.initials: M
authors.lastname: Sunagawa
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D015780:Carbapenems / Q000737:chemistry*; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D000077731:Meropenem; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D013845:Thienamycins / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D013845:Thienamycins; C113167:desmethyl meropenem; D000077731:Meropenem