- Ureidobenzotriazine multiple H-bonding arrays: The importance of geometrical details on the stability of H-bonds
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(Chemical Equation Presented) A 3-ureidobenzo-1,2,4-triazine 1-N-oxide (1) was synthesized successfully. The derivative displays an acceptor-donor- acceptor-acceptor (ADAA) hydrogen-bonding motif in CDCl3 and DMSO-d6 solution as well as in the solid state. Although moderately strong association of 1 was observed with DAD motifs, nonspecific binding is observed with ureidopyridines featuring a complementary DADD array. Density functional calculations of conformations 1a and 1b together with two complexes revealed the clearly nonplanar geometry of the multiply hydrogen-bonded complex, in which some bonds are significantly longer (3.2 A) than is optimal for H-bonds. As a result, only very small free energies of association were calculated, in line with the experimentally observed absence of specific assembly of the components.
- Ligthart,Guo, Dawei,Spek,Kooijman, Huub,Zuilhof, Han,Sijbesma, Rint P.
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- Iron-promoted sulfur sequestration for the substituent-dependent regioselective synthesis of tetrazoles and guanidines
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We have established a facile and versatile synthetic methodology for the construction of tetrazoles and guanidines in the presence of an eco-friendly, inexpensive, easily available iron reagent. Aromatic thioureas with electron-donating substituents produced their respective target products in quantitative yield. In contrast, when electron-withdrawing substituted aromatic thioureas were used, the expected products were obtained in reduced yield. However, the desired products were obtained in good yield at moderate temperature. In addition, mechanistic studies revealed that the synthetic route involved iron-based subsequent reactions of addition and removal of sulfur.
- Pendem, Venkata Bhavanarushi,Tamminana, Ramana,Nannapaneni, Madhavi
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p. 499 - 509
(2021/04/09)
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