Di-tert-butyl 2,2′-[(2-hydroxyethyl)azanediyl]diacetate

In the title compound, C14H27NO5, the hydroxy group and one of the acetate carbonyl O atoms are linked by an intramolecular O—H⋯O hydrogen bond, forming an eight-membered ring. This interaction gives rise to an asymmetric molecular conformation.


D-HÁ
to obtain some new imaging agents labelled by 99m Tc core. Here we report the crystal structure of the title compound which can be used as a precursor in the synthesis of aminodiacetate derivatives.
The molecule of the title compound is shown in Fig. 1. The molecular conformation is to a large extentd determined by the intramolecular hydrogen bond O(5)-H(5)···O(2) ( Table 1) which is a part of the eight-

Experimental
Tert-butyl 2-bromoacetate (22 g, 114 mmol) and KHCO 3 (13 g, 130 mmol) were dissolved in DMF (100 ml) at 0°C. Then 2-aminoethanol (3.2 ml, 50 mmol) was added to the solution in drops within 1 h. After adding 2-aminoethanol, the solution was heated at 55 °C for 20 h. Subsequently, the mixture was washed by the saturated NaHCO 3 solution and the crude product was extracted by ethyl acetate. After that, the organic phase was washed by saturated NaCl solution and the new organic phase was then dried by Na 2 SO 4 for 48 h. After filtering the solution, the crude product was obtained. The crude product was recrystallized from ethyl acetate giving colorless block crystals of the title compound suitable for the single-crystal X-ray diffraction. IRnfrared Spectrum: 3438.3 cm -1 ; 2978.5 cm -1 ; 2933.7 cm -1 ; 1456.8 cm -1 ; 1393.6 cm -1 ; 1732.0 cm -1 ; 1368.6 cm -1 ; 1223.5 cm -1 ; 1070.9 cm -1 ; 1150.5 cm -1.

Refinement
The H atoms bound to C atoms were introduced in idealized positions (C-H = 0.96-0.97 Å) and allowed to ride on their respective parent atoms with U iso (H) =1.2 U eq (C). The H atom from the hydroxy group was located in a difference Fourier synthesis and in the refinement the O-H distance was restrained to 0.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(F 2 ) is used only for calculating R-factors(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.