tert-Butyl N-[3-hy-droxy-1-phenyl-4-(pyrimidin-2-ylsulfan-yl)butan-2-yl]carbamate monohydrate

Crystallographic and computational study of t-butyl N-[3-hydroxy-1-phenyl-4-(pyridin- 2-ylsulfanyl)butan-2-yl]carbamate and its pyrimidin-2-yl analogue

The crystal structure analysis of the biologically-relevant title compound (1) shows the carbonyl-O2 and amide-H atoms to be anti, and perpendicular relationships between the carbamate residue and the pyridyl ring [dihedral angle=84.60(10)°] and between the carbamate and aryl ring [74.84(11)°]; the rings are approximately co-planar [12.07(17)°]. An intramolecular hydroxyl-O–H···N(pyridyl) hydrogen bond that closes a S(7) loop is noted. Of interest is the observation that this hydrogen bond is not found in the structure of the pyrimidinyl analogue (2) which was characterised as a monohydrate, i.e. 2·H2O, in an earlier study. Density-functional theory calculations show the observed conformation in 1 is 2.0 kcal/mol more stable than the conformation where the intramolecular hydrogen bond is absent. This energy difference reduces to ca 0.5 kcal/mol in the case of 2. The differences in molecular conformations found for 1 and 2 are therefore ascribed to the dictates of overall molecular packing, in particular due to the influence of lattice water in 2·H2O.

N-{(2S)-3-Hy-droxy-4-[(5-methyl-1,3,4-thia-diazol-2-yl)sulfan-yl]-1-phenyl-2-but-yl}-4-methyl-benzene-sulfonamide

The thia-diazoyl and sulfonyl-benzene rings in the title compound, C(20)H(23)N(3)O(3)S(3), are aligned to the same side of the mol-ecule, forming a twisted 'U' shape [dihedral angle = 77.6 (5)°]. The benzyl-benzene ring is orientated in the opposite direction from the mol-ecule but projects approximately along the same axis as the other rings [dihedral angle between benzene rings = 28.2 (5)°] so that, overall, the mol-ecule has a flattened shape. The hy-droxy and amine groups are almost syn which enables the formation of inter-molecular hy-droxy-OH⋯N(thia-diazo-yl) and amine-H⋯O(sulfon-yl) hydrogen bonds leading to a supra-molecular chain aligned along the a axis.