EFFECT OF MICELLES ON CYCLIZATION REACTIONS - THE USE OF N-HEXADECYL-2-CHLOROPYRIDINIUM IODIDE AS AN AMPHIPHILIC CARBOXYL-ACTIVATING AGENT IN LACTONIZATION AND LACTAMIZATION

Lactonization and lactamization with a novel carboxyl-activating agent, N-hexadecyl-2-chloropy-ridinium iodide (C(16)PyCl,I), were investigated. The organization of this agent in micelles in the reaction medium facilitates cyclization giving rise to a micellar effect. Under these conditions, the corresponding lactam is produced from the omega-amino acid 12-aminododecanoic acid in good yield (double that obtained-with the Mukaiyama reagent, N-methyl-2-chloropyridinium iodide C(1)PyCl,I). On the other hand, the yield of lactone from 16-hydroxyhexadecanoic acid was the same with either carboxyl-activating agent. These results were accounted for in terms of substrate-dependent micellar effects. Because of solubility effects, the omega-amino acids and omega-hydroxy acids are not localized in comparable ways vis a vis the interface and, thus, have different reactivities. Moreover, hydrolysis of the reagents, C(16)PyCl,I and C(1)PyCl,I, was also detected. The interference of this reaction with the cyclization process was also found to depend on a micellar effect with C(16)PyCl,I that is not observed with C(1)PyCl,I.