Non-empirical calculations of NMR indirect spin-spin coupling constants. Part 13: configurational assignment of aminosulfonylamidines.
Carbon-carbon coupling constants have been experimentally measured using the INADEQUATE pulse sequence in the series of N-[1,2-bis(dialkylamino)-2-arylethylidene]arylsulfonamides obtained from N-(1-aryl-2,2,2-trichloroethyl)amides of arylsulfonic acids. Comparison of the experimental J(C,C) in this series with those calculated at the SOPPA (Second-Order Polarization Propagator Approach) level in the model aminosulfonylamidine provided an unambiguous assignment at the C=N bond of the eight-title aminosulfonylamidines to E-configuration, while the unknown J(C,C) couplings in their inaccessible diverse Z isomers have been predicted with high reliability. The established marked difference between J(C,C) of the corresponding carbon-carbon bonds in cis and trans orientations to the nitrogen lone pair in aminosulfonylamidines provides a powerful tool in the configurational assignment at the C=N bond in a wide series of the related systems containing the C=N-SO2R moiety.
Krivdin
Leonid B
LB
A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033 Irkutsk, Russia. krivdin@irk.ru
Larina
Lyudmila I
LI
Chernyshev
Kirill A
KA
Rozentsveig
Igor B
IB
D000578:Amidines / Q000737:chemistry*; D002247:Carbon Isotopes; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards; D008958:Models, Molecular; D015394:Molecular Structure; D012015:Reference Standards; D013237:Stereoisomerism
D000578:Amidines; D002247:Carbon Isotopes