Jaime Ríos-Motta

7-(Imidazolidin-1-ylmethyl)quinolin-8-ol: An Unexpected Product from a Mannich-type Reaction in Basic Medium

7-(Imidazolidin-1-ylmethyl)quinoline-8-ol, an N-substituted imidazolidine, was synthesized in a one-step reaction between 1,3,6,8-tetraazatricyclo[4.4.1.1 3,8 ]dodecane (TATD) and 8-hydroxyquinoline. Obtaining this substance enhanced the scope of possibilities in the synthesis of unsymmetrically N,N-disubstituted imidazolidines. 1 H-NMR spectral studies revealed that this type of substance does not undergo ring-chain tautomerism.

2,2′-[Imidazolidine-1,3-diylbis(methyl­ene)]diphenol

In the title molecule, C17H20N2O2, the imidazolidine ring adopts a twist conformation. The mean plane through the five atoms of the imidazolidine ring makes dihedral angles of 70.18 (4) and 74.14 (4)° with the planes of the two aromatic rings. The dihedral angle between the benzene rings is 53.11 (5)°. Both phenol –OH groups form intramolecular hydrogen bonds to the N atoms, with graph-set motif S(6). In the crystal, pairs of O—H⋯O hydrogen bonds link the molecules into dimers with R 4 4(18) ring motifs. The crystal packing is further stabilized by C—H⋯O and weak C—H⋯π interactions.

4,4′-Dichloro-2,2′-[imidazolidine-1,3-diylbis(methylene)]diphenol

The imidazolidine ring in the title compound, C17H18Cl2N2O2, adopts a twist conformation. The observed conformation is stabilized by two intramolecular O—H⋯N hydrogen bonds, with both N atoms acting as hydrogen-bond acceptors. The phenyl substituents are aligned at 70.0 (1) and 76.6 (1)° with respect to the best plane through the five atoms of the imidazolidine ring. Weak intermolecular C—H⋯O interactions stabilize the crystal packing.

Synthesis and structural studies of a new class of quaternary ammonium salts, which are derivatives of cage adamanzane type aminal 1, 3, 6, 8-tetraazatricyclo[4.3.1.13,8]undecane (TATU).

BackgroundNovel mono N-alkyl quaternary ammonium salts (3a-f) were prepared using the Menschutkin reaction from the cage adamanzane type aminal 1,3,6,8-tetraazatricyclo[4.3.1.13,8]undecane (TATU) and alkyl iodides, such as methyl, ethyl, propyl, butyl, pentyl and hexyl iodide (2a-f), in dry acetonitrile at room temperature.ResultsThe structures of these new quaternary ammonium salts were established using various spectral and electrospray ionization mass spectrometry (ESI-MS) analyses. Compound (3b) was also analyzed using X-ray crystallography.ConclusionIt was noted that alkyl chain length did not significantly affect the reaction because all employed alkyl iodide electrophiles reacted in a similar fashion with the aminal 1 to produce the corresponding mono N-quaternary ammonium salts, which were characterized by spectroscopic and analytical techniques.

3,3'-(Ethane-1,2-di-yl)bis-(6-methyl-3,4-dihydro-2H-1,3-benzoxazine).

The asymmetric unit of the title compound, C20H24N2O2, contains one half-molecule, which is completed by inversion symmetry. In the crystal, molecular chains are formed through non-classical C—H⋯O hydrogen bonds, formed between axial H atoms of the oxazine ring and a O atom of a neighboring molecule.

3,3′-Ethyl­enebis(3,4-dihydro-6-chloro-2H-1,3-benzoxazine)

The asymmetric unit of the title compound, C18H18Cl2N2O2, contains one half of an independent molecule, the other half being generated via a centre of inversion at the molecular centroid. In the crystal structure, molecular chains are formed through non-classical C—H⋯ O hydrogen bonds between an axial H atom of the oxazine ring and the O atom of a neighbouring molecule.

3,3′-(Ethane-1,2-di­yl)bis­(3,4-dihydro-2H-1,3-benzoxazine)

The title compound, C18H20N2O2, was prepared by Mannich-type reaction of phenol, ethane-1,2-diamine and formaldehyde. The heterocyclic rings adopt half-chair conformations. The acyclic methylene groups attached to the N atoms are in an axial position. In the crystal, weak C—H⋯O hydrogen bonds link the molecules into dimers. These dimers are further connected via C—H⋯π contacts.

4,4'-Difluoro-2,2'-[imidazolidine-1,3-diylbis(methyl-ene)]diphenol.

The imidazolidine ring in the title compound, C19H24N2O2, adopts a twist conformation and its mean plane (r.m.s. deviation = 0.19 Å) makes dihedral angles of 72.38 (9) and 71.64 (9)° with the two pendant aromatic rings. The dihedral angle between the phenyl rings is 55.94 (8)°. The molecular structure shows the presence of two intramolecular O—H⋯N hydrogen bonds between the phenolic hydroxyl groups and N atoms with graph-set motif S(6). In the crystal, C—H⋯O hydrogen bonds lead to the formation of chains along the b-axis direction.

FT-IR and DFT studies of the proton affinity of small aminal cages.

The proton affinity scale of small aminal cages was investigated using experimental and theoretical methodologies. The formation constant (K(f)) was determined for 1:1 hydrogen-bonded complexes between p-fluorophenol (PFP) and some aminal cage type (B) in CCl(4) at 298 K using FT-IR spectrometry. Then, the total interaction energy (E(PFF***B)), the energy of protonation (E(HB+)), the HOMO-LUMO GAP values and the Fukui index were calculated using the DFT/B3LYP/6-31 G(d,p) level of theory as theoretical descriptors. The values of the formation constant and energy changes vary with the tetrahedral character of the nitrogen lone pair. Good correlation between experimental and theoretical scales was observed, evidence for the existence of a relationship between the total energy of interaction calculated by structural parameters and the proton affinity in this series.

X-ray and Hydrogen-bonding Properties of 1-((1H-benzotriazol-1-yl)methyl)naphthalen-2-ol

The solid state structure of 1-((1H-benzotriazol-1-yl)methyl)naphthalen-2-ol, C17H13N3O, shows that this Mannich base crystallizes forming intermolecular N⋯HO hydrogen bonds, rather than intramolecular ones. Factors contributing to this choice of hydrogen-bonding mode are discussed. The compound crystallizes in the monoclinic system, P21/c space group, with lattice constants: a = 11.7934(9) Å, b = 14.3002(14) Å, c = 8.4444(8) Å, β = 106.243(5) deg, V = 1367.3(2) Å3, Z = 4, F(000) = 576, R1 = 6.96%, wR2 = 11.4%.