Poly(2-imidazolin-5-ones)—A new class of heterocyclic polymers

The reaction of bisazlactones (2-oxazolin-5-ones) with primary diamines containing additional secondary or tertiary amine functionality (e.g., diethylenetriamine, triethylenetetramine, or N-methyliminobispropylamine) readily produces polyamides which serve as precursors to a new class of heterocyclic polymers. Thermal cyclodehydration takes place under relatively mild conditions (180–200°C) to produce water-soluble polymers containing the 2-imidazolin-5-one heterocycle. Model reactions have been studied to verify this mode of cyclization and confirm the proposed polymer structure.     

Further polymers derived from bisazlactones and tetraamino compounds

New polymers containing benzimidazole in the polymeric backbone were obtained from the reaction of bis(oxazolones) with known and with a novel aromatic tetraamine. The polymers have inherent viscosities in the range of 0.1-0.4 dL/g (in DMF 30°C).     

Unimolecular and bimolecular transfer of N-substituents from pyridinium cations: Evidence for a clear mechanistic changeover

$\text{N}$-Substituents in 2, 4, 6-triphenylpyridiniums are transferred to piperidine, morpholine and pyridine by unimolecular and/or bimolecular processes in chlorobenzene solution. These processes are quite distinct and afford no evidence for a mechanism intermediate between S_N1 and S_N2.     

The reactions of arylamines with chelidonic acid

Depending on the conditions, and the basicity of the amine, arylamines react with chelidonic acid to yield five different types of product: salts, N-arylchelidamic acids, N-aryl-4-pyridone-2-carboxylic acids, N-aryl-4-pyridones, or chelidamic acid itself.     

A Novel Synthesis of Benzothiazoles

Substituted azlactones react in acetic acid smoothly with o-aminothiophenol to give good yields of 2-(α-amidoalkyl)benzothiazoles.     

Nucleophilic displacement of N-benzyl groups: effect of pyridinium on rates and mechanism

Steric acceleration by α-substituents in pyridine leaving groups is quantitatively assessed. Constraint of α-phenyls to near planarity forms superior leaving groups for S_N2 displacements. α-t-Butyl groups significantly increase S_N1 dissociation.