On the Reaction Mechanism of the Selective C(sp3)–H Functionalization of N -Benzylpiperidines Mediated by TEMPO Oxoammonium Cation.

The G SP ‡ sp for route III SB (N=O---H) sb is 5.76 kcal/mol, while the G SP ‡ sp for route IV SB (H---N=O) sb is 7.71 kcal/mol. On the Reaction Mechanism of the Selective C(sp³)-H Functionalization of N -Benzylpiperidines Mediated by TEMPO Oxoammonium Cation Keywords: selectivity; C-H oxidation; alkoxyamino lactams; oxoammonium salt of TEMPO; sodium chlorite EN selectivity C-H oxidation alkoxyamino lactams oxoammonium salt of TEMPO sodium chlorite 3662 3669 8 10/19/23 20231102 NES 231102 Graph It is now well-recognized that both 2,2,6,6-tetramethylpiperidine-1-oxoammonium cation (TEMPO SP + sp , B A b ) and its 4-amine-analogue cation 4-AcNH-TEMPO SP + sp are mild and selective oxidizing reagents of primary and secondary alcohols to their respective carbonyl compounds. On the other hand, comparing route I SB (N=O---H) sb and route III SB (N=O---H) sb , we note that despite the I exo i C-H bond being weaker than the I endo i C-H bond, [36] the latter hydrogen is slightly positive, [17] and a small but significant increase in the activation energy of 0.66 kcal/mol is observed. [Extracted from the article]