1.3.5.7- Tetraazadecalins, conformational

The results, presented in Table 8, show that in most cases the conformer with the lowest steric energy indeed corresponds to the experimentally most favored one. In addition, several molecules containing the N—C—N moiety were retrieved from the Cambridge Structural Database and calculated with the new parameter set. A comparison between MM2 and X-ray geometries (selected structural parameters only) for two conformers of 1,4,5,8-tetraazadecalin (25, 26) is provided in Table 9 and shows good fit between the experimental and calculated data. 

Both theoretical and experimental studies have been reported for as- and /ra r-l,3,5,7-tetraazadecalin systems 66 and 67 <1996AJC285, 1998JOC8850>. The former is reportedly more stable as the iV-inside form 66a (calc. AH( 29.6 kj mol ) than as the A -outside form 66b (calc. AH( 56.3 kj mol ), although the two forms exist in equilibrium. The more crystalline trans-form 67 again exists in two all-chair conformations, 67a and 67b, of which the former (calc. AH I 37.8 vs. 46.1 kJ mol for R = H) is more stable <1996AJC285>. The conformational effect of changing the 2- and 6-substituents is reportedly small. 

L., Ganguly, B., Fuchs, B. (1998). The 1,3,5,7-tetraazadecalins structure, conformation, and stereoelectronics. Theory vs. experiment. Journal of Organic Chemistry, 63, 8850-8859. (b) Ritter, 1., Gleiter, R., Imgartinger, H., Oeser, T. (1997). Conformations of Azacyclodeca-3,8-diynes and l,6-Diazacyclodeca-3,8-diynes and the Generalized Anomeric Effect A Test for Current Conformational Models for Azaheterocycles. Journal of the American Chemical Society, 119, 10599-10607. 

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