engleski

Computational study of triguanide cyclization

Recently, we prepared series of novel pentasubstituted triguanide derivatives1 starting from appropriately monosubstituted guanidines and N, N'-diisopropylcarbodiimide. In some cases, however, this reaction led to formation of cyclic products which were found to be 1, 2, 4, 6-tetrasubstituted derivatives of 1, 3, 5-triazine. For instance, in an attempt to prepare triguanide 3 starting from N, N-dimethylguanidine (1) and N, N'-diisopropylcarbodiimide (2), the only isolated product was 1, 3, 5-triazine derivative 4, as shown in Scheme 1. The product 4 was spectroscopically characterized and its structure confirmed by X-ray diffraction of the perchlorate salt.2 In this work, results of computational study on cyclization of hexamethyltriguanide (CH3- instead of (CH3)2CH- groups in structure 3) to the corresponding triazine will be presented. Geometry optimizations and vibrational analyses were carried at DFT level of theory using B3LYP/6-31G(d) approach. In addition, single point calculations using B3LYP/6-311+G(d, p) method were carried out. The results indicate that the cyclization proceeds via two-step mechanism with the first step being formation of intermediate heterocyclic structure followed by elimination of methylamine, which results in formation of triazine 4.

triguanide cyclization; computational study

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