“…Methylene groups in α position to an amide (11‐CH 2 for compound 14 , 12‐CH 2 for 15 , 11‐CH 2 , 18‐CH 2 for compounds 16 ) are more de‐shielded, and therefore have the highest chemical shift. The protonation of primary and secondary amine functional groups causes a de‐shielding of the methylene functional group α to the nitrogen atom, causing a downfield shift by ≈1 ppm [9] . Therefore, CH 2 groups located next to an amine are more de‐shielded than those located further away, (1‐CH 2 , 3‐CH 2 , 5‐CH 2 , 7‐CH 2 , 9‐CH 2 for 14 , 1‐CH 2 , 3‐CH 2, 5‐CH 2 , 8‐CH 2, 10‐CH 2 for 15 , and 1‐CH 2 , 3‐CH 2 , 5‐CH 2 , 7‐CH 2 , 9‐CH 2 , 20‐CH 2 , 22‐CH 2 , 25‐CH 2 , 27‐CH 2 , 29‐CH 2 for 16 ).…”