The effect of intramolecular-hydrogen bonds in the synthesis of novel imidates from a 13-membered dioxadithia crown ether diester

摘要

The synthesis and structural properties of three novel imidates, 11,13-bis-(2-amino-ethylimino)-1,10-dioxa-4,7-dithiacyclotridecane (2),11,13-bis-(3-aminopropylimino)-1,10-dioxa-4,7-dithiacyclotridecane, (3) and 2,11-dioxa-5,8-dithia-13,16,19,22-tetraazabicyclo[10.10.1]tricosa-1(22),12 -diene, (4) have been described. These compounds were synthesized by treating 1,10-dioxa-4,7-dithiacyclotridecane-11,13-diester (1) with the appropriate diamine under N-2 and their structures have been characterised by elemental analyses, H-1- and C-13-nmr, ir, and mass spectral studies. Elemental analyses and spectroscopic data support the proposed imidate structures. In addition, total energy and heat of formation (Figure 2) calculated for imidates 2a-4a and 2b-4b by the semiempirical AM1 calculations have shown that imidates 2b-4b having intramolecular hydrogen bonds are more stable (5-10 kcal/mol) than compounds 2a-4a. [References: 34]