Piperidine, 2,2,6,6-tetramethyl hydrochloride

Piperidin-4-one, 1-hydroxy-2,2,6,6-tetramethyl-conformation, 2, 117 Piperidin-4-one, 2,2,6,6-tetramethyl-hydrochloride conformation, 2, 114... 

Distortion of the chair conformation by substitution occurs in 2,2,6,6-tetramethyl-piperidin-4-one hydrochloride (45) (71AX(B)932), in which steric interaction between axial methyl groups leads to flattening of the ring. The resultant C(2)—C(6) intramolecular distance is 3.2 A, to be contrasted with 2.4 A in the non-methylated compound. A similar effect is to be found in other 2,2,6,6-tetramethyl derivatives (81AX(B)1771). In the related free radical nitroxide (46) the steric interactions are reduced by adoption of a symmetric twist chair form (74AX(B)790). 4-Chloro-5-methylamino-2,3,6-pyridinetrione monohydrate... 

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