tert-Butyl N-[(S)-1-hydrazinecarbonyl-2-hydroxyethyl]carbamate

In the title compound, C8H17N3O4, the dihedral angle between the hydrazinecarbonyl and carbamate groups is 44.94 (12)°, and the carbonyl groups are anti to each other. In the crystal, the hydroxy group forms an O—H⋯Na (a = amine) hydrogen bond and each of the four N—H atoms forms an N—H⋯O hydrogen bond; the hydrazinecarbonyl O atom accepts two such bonds. This results in two-dimensional arrays in the ab plane, mediated by the hydrogen bonding, sandwiched by tert-butyl groups.

In the title compound, C 8 H 17 N 3 O 4 , the dihedral angle between the hydrazinecarbonyl and carbamate groups is 44.94 (12) , and the carbonyl groups are anti to each other. In the crystal, the hydroxy group forms an O-HÁ Á ÁN a (a = amine) hydrogen bond and each of the four N-H atoms forms an N-HÁ Á ÁO hydrogen bond; the hydrazinecarbonyl O atom accepts two such bonds. This results in two-dimensional arrays in the ab plane, mediated by the hydrogen bonding, sandwiched by tertbutyl groups.

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The carbonyl-O1 and O3 atoms lie to opposite sides of the molecule as seen in the pseudo O1-C1···C4-O3 torsion angle of -176.7 (3) °. Finally, each of the N-H groups is anti to the adjacent carbonyl so that the N-H groups, too, lie to opposite sides of the molecule. Although the absolute structure could not be determined experimentally, the assignment of the S-configuration at the C2 atom is based on the starting reagents. There are five acidic H atoms in the structure, and each of these forms a significant hydrogen bonding interaction, Table 1
The residue was columned chromatographed on silica gel using a gradient of 0 to 5% chloroform in methanol, affording the title compound as a white solid in 70% yield. The crystals used in the structural study were grown from EtOH solution, m. supplementary materials sup-2 = 1.2U eq (N). In the absence of significant anomalous scattering effects, 1067 Friedel pairs were averaged in the final refinement. Fig. 1. The molecular structure of (I) showing displacement ellipsoids at the 50% probability level.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating Rfactors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.