Spirocyclic 2,5-dihydro-1H-imidazole 1-oxyl radicals with a mesogenic substituent on C4. Synthesis and crystal structure

The synthesis of new functionalized 1,3,5-triazine-based stable bi- and trinitroxides of the 2,5-dihydroimidazole series

“…39 The geometry of the 3phenyl-1,4-diazaspiro[4.5]dec-3-ene 1-oxyl moiety is almost similar to that in 2,2-dimethyl-3-[4-(decyloxy)phenyl]-1,4-diazaspiro[4.5]dec-3-ene 1-oxyl. 34 The dihedral angle between the phenyl and 2,5-dihydroimidazole planes is 4.2(2). It is worth noting that the formed layers are parallel to the ab plane owing to the C6-H…O2 interaction (the H…O distance: 2.38, the C-H…O angle: 140) in the crystal packing of triradical 1a.…”

“…To synthesize paramagnetic compounds 1a-c and 2a-c, we applied a nucleophilic substitution reaction of cyanuric chloride or 2,4-dichloro-6-methoxy-1,3,5-triazine and the corresponding derivatives of spirocyclic 2,5dihydroimidazole-type monoradicals 3, 34 4, and 5 containing a 4-hydroxyaryl residue in the presence of a base (Figure 2). In this regard, first, we describe the preparation and structural characterization of novel nitroxides 4 and 5.…”

“…33 The present report continues our research on the synthesis of functional derivatives of spirocyclic monoand oligoradicals of the azole series. [34][35][36] The present paper describes the synthesis as well as structural characterization of new paramagnetic derivatives of 2,4,6-tris(aryloxy)-1,3,5-triazine (1a-c) and of 2,4bis(aryloxy)-6-methoxy-1,3,5-triazine (2a-c; Figure 1).…”

Spirocyclic Nitroxides as Versatile Tools in Modern Natural Sciences: From Synthesis to Applications. Part I. Old and New Synthetic Approaches to Spirocyclic Nitroxyl Radicals

“…HAK 250 (R = H), bearing an additional functional phenolic group, has been employed for the synthesis of SNRs possessing one or two mesogenic groups. For this purpose, compounds 250 (R = H, C n H 2n+1 ) are condensed with a cycloxexanone [ 157 ] or with its four-substituted functional derivatives, 4-(4-hydroxyphenyl)cyclohexanone [ 158 ] and 4-hydroxycyclohexanone [ 159 ]. After the oxidation of intermediate N -hydroxy derivatives to SNRs 251 , the latter are acylated by means of one or two residues of 4-alkoxybenzoic acids to form corresponding paramagnetic esters 252 (one of examples is shown in Scheme 44 ).…”

New spirocyclic nitroxides of 2,5-dihydroimidazole series flanked by two mesogenic fragments

“…[17][18][19][20][21][22] Interesting results were obtained in the preparation ferroelectric LC`s on the basis of triangular structures (3+3+3) 23,24 and gem-difluoro derivatives of spirocyclopropanes (3+6+3), 25 which showed chiral smectic SmA* and SmC* phases in different conditions. This report is a continuation of the researches on the synthesis of spirocyclic mono-and biradicals of azole series which can show mesogenic properties [26][27][28] and serve as spin probes for diamagnetic LCs by ESR spectroscopy. 29,30 In this work we describe an approach to the synthesis of stable spirocyclic nitroxides 2-4 with a 2,5-dihydroimidazole structure ( Figure 1).…”