1,3-Bis(3-tert-butyl-2-hydroxy-5-methoxybenzyl)hexahydropyrimidin-5-ol monohydrate

Abstract

The asymmetric unit of the title compound, C28H42N2O5·H2O, consists of one half of the organic mol­ecule and one half-mol­ecule of water, both of which are located on a mirror plane which passes through the central C atoms and the hydroxyl group of the heterocyclic system. The hydroxyl group at the central ring is disordered over two equally occupied positions. The six-membered ring adopts a chair conformation, and the 2-hy­droxy­benzyl substituents occupy the sterically preferred equatorial positions. The aromatic rings make dihedral angles of 75.57 (9)° with the mean plane of the heterocyclic ring. The dihedral angle between the two aromatic rings is 19.18 (10)°. The mol­ecular structure features two intra­molecular phenolic O—H⋯N hydrogen bonds with graph-set motif S(6). In the crystal, mol­ecules are connected via O—H⋯O hydrogen bonds into zigzag chains running along the a-axis direction.

Crystal structure of 1,3-bis(3-tert-butyl-2-hydroxy-5-methylbenzyl)-1,3-diazinan-5-ol monohydrate

“…These interactions stabilize the molecular conformation, with O1Á Á ÁN1 = 2.696 (5) and O2Á Á ÁN2 = 2.702 (5) Å . These distances are closely comparable to those observed in the related structure (II) (Rivera et al, 2014). The molecular structure of the title compound.…”

“…The N2-C7 distance of 1.485 (6) Å is slightly longer than the typical value for an N-C bond [1.469 Å ]. The remaining C-N bonds in the molecule are also typical and compare well with those found in the the related structure (II) (Rivera et al, 2014). The C12-O1 and C22-O2 distances are typical of those for a hydroxy substituent on an aromatic ring [1.376 (6) and 1.374 (5) Å , respectively].…”

“…Apart from the previously published structure (Rivera et al, 2014), there is only one similar entry in the CSD (Mendes et al, 2014). In this latter structure, the 1,3-diazinane molecule acts as a ligand to an iron(III) cation, which would affect comparisons with the geometric parameters of the title compound.…”

“…We have previously reported the synthesis and crystal structure of 1,3-bis(3-tert-butyl-2-hydroxy-5-methoxybenzyl)-1,3-diazinan-5-ol monohydrate (II) and this study has shown that the hydroxyl substituent on the 1,3-diazinane ring is disordered over two positions, namely one component equatorial and the other axial (Rivera et al, 2014). As a logical step in the progression of these studies, in this paper we discuss the synthesis and crystal structure of the title compound (I), 1,3bis(3-tert-butyl-2-hydroxy-5-methylbenzyl)-1,3-diazinan-5-ol…”

Synthesis of 5-Hydroxydihydropyrimidine Derivatives and the Influence of Intramolecular Hydrogen Bonding on Their NMR Properties and Conformational Preferences of the Hydroxyl Group

“…This red shift of the O-H stretching wavenumber is due to strong inter-or intramolecular hydrogen bonding, which is in agreement with our previous X-ray structural research in which two intramolecular hydrogen bonds were observed in the molecular structure of 1,3-bis(3-tert-butyl-2hydroxy-5-methoxybenzyl)hexahydropyrimidin-5-ol (2b) monohydrate. 10 The IR spectra of the compounds also showed a characteristic absorption band with a strong intensity of the C-O stretching of phenol, which appears at 1219 cm -1 , and an absorption band at approximately 1100 cm -1 , which is characteristic of the a polarized C-N bond. The formation of a hydrogen bond between this group and the adjacent phenolic group is responsible for the low absorption frequency, therefore confirming the formation of Mannich bases.…”