Synthesis And Structure Of 9-Nitrosojulolidine

A 1H n.m.r. study of internal rotation in the hitherto unknown 9-nitrosojulolidine (I) yields ΔH‡= 17·1(±1·5) kcal mol–1 and ΔS‡= 11·6 ± 6 cal K–1 mol–1 for rotation of the nitroso-group; an appreciably lower resistance is found for the analogous formyl group rotation in isoelectronic 9-formylijulolidine(III), the corresponding activation parameters being ΔH‡= 11·9 ± 1·0 kcal mol–1 and ΔS‡= 3·9 ± 4 cal K–1 mol–1.