Proton affinities and the site of protonation of enamines in the gas phase

N- vs. C-protonation of captodative trifluoromethylated enamines: A theoretical study

“…5). Large difference between these values (DPA) for the C-and N-protonated forms of compound 1d -14.37 (E) and 10.77 kcal/mol (Z) -is in agreement with the experimental data on the C-protonation of enamines [1][2][3][4][5]34]. Besides, it was theoretically found that preferred C-protonation of vinylamine and similar structures is the result of stability of the carbocations due to delocalization of the positive charge [35].…”

“…The problem seemed to be solved in the early 80's when it was theoretically proved that the C b -protonation is favored by up to 18.7 kcal/mol [3] over the N-protonation which is in agreement with the ICR experiment [4]. The later, more sophisticated calculations at the MP2 and DFT level approved the preference of the C b -protonation [5].…”

Aza Cope Rearrangement of Propargyl Enammonium Cations Catalyzed By a Self-Assembled “Nanozyme”

“…Anhydrous solvents were dried over activated alumina under nitrogen pressure and sparged with nitrogen before use. 47 N,N-dimethylisobutenylamine, 48 4-methyl-2-hexynol 49 , and 5-methyl-2-hexynol 50 were prepared according to published procedures.…”

Anionic polymerization of Lewis acid-activated methyl methacrylate by enamines

“…A pyrrolidinyl-type enamine is known to be slightly more basic than its piperidinyl analogue and much more basic than its morpholinyl analogue. 19 The data in Table III indicate the same tendency; the pK a values in 50% aq EtOH indicate that, for example, 1a (pK a ϭ 10.9) is more basic than either 1h (10.3) or 1i (8.3). The polymerization failed when the enamines of low basicity (1e and 1i) or those having two ␤-substituents (1e and 1j) were employed.…”