CONFORMATIONAL-ANALYSIS OF SATURATED HETEROCYCLES .90. SYNTHESES AND CONFORMATIONAL-ANALYSIS OF 1,2,4-TRIMETHYL-1,2,4-TRIAZACYCLOHEXANES AND 1,2,3,4-TETRAMETHYL-1,2,4-TRIAZACYCLOHEXANES

The first syntheses are described of saturated 1,2,4-triazacyclohexanes. The 1,2,4-trimethyl derivative exists predominantly in the eae conformation: at lower temperatures minor amounts of eee⇌eea (ca. 10%) and then aee (ca. 5%) are frozen out. Kinetic and thermodynamic parameters are obtained from variable-temperature 13C n.m.r. spectra. ' Passing' (ΔG c‡ ca. 12 kcal mol-1) and ' non-passing ' (ΔGc‡ ca. 8 kcal mol-1) nitrogen-inversion barriers are clearly differentiated.