S-Functionalization of 3,5-bis(2-pyridyl)-1,2,4,6-thiatriazine: probing the effect of alkyl chain length in the development of tethered materials†
Abstract
Reactions between 3,5-bis(2-pyridyl)-4-hydro-1,2,4,6-thiatriazine (Py2TTAH) and a series of 1,n-dibromoalkanes (n = 2, 3, 4, 5, 6, 8, 10) were explored and a synthetic route to prepare tethered 3,5-bis-(2-pyridyl)-1λ4,2,4,6-thiatriazines is described. When the length of the alkyl group employed is n ≥ 4, S,S′-alkyl-bis(Py2TTA) derivatives (8–12) are isolated; however, if n < 4, S-cyclopropyl-Py2TTA (13; n = 3) and S-ethenyl-Py2TTA (14; n = 2) are formed due to competitive intramolecular SN2 cyclization and E2 reactions, respectively. NMR spectroscopy, electron spray ionization mass spectrometry and X-ray crystallography were used to probe the dependence of the alkyl chain length on the reaction pathway. Computational studies are also presented, which support the preference of intramolecular vs. intermolecular SN2 reactions when n = 3 and n > 3, respectively.