trans-4-(2-Amino-5-bromo-6-methylpyrimidin-4-ylamino)-1-methylcyclohexanol

The title compound, C12H19BrN4O, represents the minor component of the two products obtained in a series of transformations involving the Grignard reaction of tert-butoxycarbonyl-protected 4-aminocyclohexanone with MeMgBr, and subsequent interaction of the obtained amino-substituted cyclohexanol with 4-chloro-6-methylpyrimidin-2-amine followed by bromination with N-bromosuccinimide. The X-ray structure showed that this product represents a trans isomer with respect to the amino and hydroxy substituents in the cyclohexyl ring; the dihedral angle between the aminopyrimidine plane and the (noncrystallographic) mirror plane of the substituted cyclohexyl fragment is 33.6 (3)°. Only two of the four potentially ‘active’ H atoms participate in intermolecular N—H⋯O and O—H⋯N hydrogen bonds, linking the molecules into layers parallel to the (10) plane.

The title compound, C 12 H 19 BrN 4 O, represents the minor component of the two products obtained in a series of transformations involving the Grignard reaction of tertbutoxycarbonyl-protected 4-aminocyclohexanone with MeMgBr, and subsequent interaction of the obtained aminosubstituted cyclohexanol with 4-chloro-6-methylpyrimidin-2amine followed by bromination with N-bromosuccinimide. The X-ray structure showed that this product represents a trans isomer with respect to the amino and hydroxy substituents in the cyclohexyl ring; the dihedral angle between the aminopyrimidine plane and the (noncrystallographic) mirror plane of the substituted cyclohexyl fragment is 33.6 (3) . Only two of the four potentially 'active' H atoms participate in intermolecular N-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds, linking the molecules into layers parallel to the (101) plane.

Related literature
For the structure of a similar N-pyrimidine derivative of aminocyclohexane, see Melguizo et al. (2003).  Table 1 Hydrogen-bond geometry (Å , ).

Comment
The Grignard reaction of tert-butoxycarbonyl(BOC)-protected 4-aminocyclohexanone, 4-C 4 H 9 OC(O)N(H)C 6 H 9 O, with MeMgBr produced the mixture of cis-and trans-4-BOC-amino-1-methyl-cyclohexanols, which was subsequently reacted with 4-chloro-6-methylpyrimidin-2-amine and then brominated with N-bromosuccinimide. The isomeric mixture of the products was separated by means of flash chromatography and the corresponding X-ray structural study of the minor isomer showed that the title compound represents a trans-isomer with respect to the amino and hydroxy substituents in the cyclohexane ring (Fig. 1). The plane of the diaminopyrimidine C1/C2/C3/C4/N1/N2/N4 fragment forms a dihedral angle of 33.6 (3)° with the approximate mirror plane of the cyclohexyl fragment, namely the plane passing through N4/C6/C9/C12/ O1. This conformation is significantly different from that observed in the related compound described in Melguizo et al., 2003, where the dihedral angle formed by the aminopyrimidine plane and the mirror plane of the cyclohexyl ring is just 13.6°.
There are four H atoms in the molecule, which are capable of H-bond formation. However, only two of them (H1 and H3A) participate in intermolecular H-bonds (Table 1), which link the molecules into layers parallel to the (1,0,-1) plane of the crystal (Fig. 2).
The U iso (H) were set to 1.2U eq of the carrying atom for methylene, methyne and amine groups, and 1.5U eq for methyl and hydroxyl H atoms. Fig. 1. Molecular structure of the title compound showing 50% probability displacement ellipsoids and atom numbering scheme; H atoms are drawn as circles with arbitrary small radius.