Nantelle S. Pantaleo

STUDIES ON THE CONFORMATIONS OF 4-N,N-DIMETHYLAMINOTHIANES AND THE CORRESPONDING METHIODIDES. EVIDENCE FROM A SINGLE CRYSTAL X-RAY DIFFRACTION ANALYSIS THAT A TWIST-BOAT CONFORMER EXISTS IN THE SOLID STATE FOR TRIMETHYL-[2,2-DIMETHYL-trans−6-PHENYLTHIAN-r-4-YL]-AMMONIUM IODIDE

Abstract A number of 4-N,N-dimethylaminothianes have been prepared by a reaction of 4-aminothianes with formaldehyde and formic acid. 1H and 13C NMR spectral analysis suggest twist conformations for 2,2-dimethyl-trans-6-phenyl-r-4-N,N-dimethylaminothiane and 2,2-dimethyl-trans-6-(4-chlorophenyl)-r-4-N,N-dimethylaminothiane. Reaction of the tertiary amines with methyl iodide gave the quaternary ammonium iodides. The 1H NMR (270 MHz) spectra of the methiodides in DMSO-d 6 indicated twist conformations for the compounds with axial C[sbnd]N bonds. The spectra also suggested a possible boat conformation for the methiodides of 2,2-dimethyl-trans-6-phenyl-r-4-N,N-dimethylaminothiane and 2,2-dimethyl-trans-6-(4-chlorophenyl)-r-4-N,N-dimethylaminothiane in equilibrium with the twist conformation. Kinetics of quaternization of six epimeric pairs of N,N-dimethylaminothianes with methyl iodide in acetonitrile at 10 ± 0.05°C have been carried out and the causes for the rate differences are discussed in terms of steric...