Synthesis and DFT analysis of non-covalent interactions in crystal structures of 6-R-2-alkoxy-, 2,3-di-, and 2,2,3-tri-tert-butylpyrrolo[1,2-b][1,2,4]triazines

Novel 7-amino-3-tert-butyl-2-OR(1)-6-R(2)-pyrrolo[1,2-b][1,2,4]triazine-8-carbonitriles (R(1) = CH(2)CO(2)Et, CH(2)Boc, Me, n-Bu; R(2) = CO(2)Et, CO(2)n-Bu, CO(2)t-Bu, C(6)H(4)CO(2)i-Pr) have been synthesized and investigated by X-ray diffraction. Nucleophilic replacement of an alkoxy group with t-BuLi afforded sterically hindered tert-butyl 7-amino-2,3-di-tert-butyl- and 2,2,3-tri-tert-butyl-8-cyanopyrrolo[1,2-b][1,2,4]triazine-6-carboxylates. The lengths and bond angles as well as packing modes of molecules in crystals have been considered. The non-covalent interactions such as the changes in the H-bonding and close contacts were analyzed by DFT and the Hirshfeld surfaces and compared for different substituents. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11224-022-02006-x.