Nuclear magnetic resonance study on the model compounds for poly( N ‐alkylglycine)s

Cis ‐ trans isomerism was investigated with N ‐acetyl and N ‐propionyl, N ‐alkylglycine dimethylamides as model compounds for poly( N ‐alkylglycine dimethlamides as model compounds for ( N ‐alkylglycine)s using n.m.r. spectroscopy. The population of the cis isomer measured in benzene and methylene chloride solutions did not show any marked dependence on the bulkiness of N ‐alkyl substituents. This contrasts with poly N ‐alkylglycine)s, whose cis isomer population increased with the introduction of bulky N ‐alkyl groups. Kinetics of the Cis ‐ trans isomerization was also investigated with N ‐acetyldimethylamides of sacrosine, N ‐ n ‐propylglycine, and N ‐isopropylglycine in tetrachloroethane solution. The δ G ‡ values for Cis ‐ trans isomerization in these amides were 18 ∼ 19 kcal/mole, which were virtually the same as that of polysacrosine.