Crystal structure of cis-2-(2-carb-oxy-cyclo-prop-yl)glycine (CCG-III) monohydrate.

Sergey Lindeman,William A Donaldson,Nathaniel J Wallock

doi:10.1107/s2056989015011500

Sergey Lindeman, William A Donaldson + Show 1 more

Open Access

https://doi.org/10.1107/s2056989015011500

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Abstract

The title compound, C6H9NO4·H2O [systematic name: (αR,1R,2S)-rel-α-amino-2-carb-oxy-cyclo-propane-acetic acid monohydrate], crystallizes with two organic mol-ecules and two water mol-ecules in the asymmetric unit. The space group is P21 and the organic mol-ecules are enanti-omers, thus this is an example of a 'false conglomerate' with two mol-ecules of opposite handedness in the asymmetric unit (r.m.s. overlay fit = 0.056 Å for one mol-ecule and its inverted partner). Each mol-ecule exists as a zwitterion, with proton transfer from the amino acid carb-oxy-lic acid group to the amine group. In the crystal, the components are linked by N-H⋯O and O-H⋯O hydrogen bonds, generating (100) sheets. Conformationally restricted glutamate analogs are of inter-est due to their selective activation of different glutamate receptors, and the naturally occurring (+)-CCG-III is an inhibitor of glutamate uptake and the key geometrical parameters are discussed.

Highlights

The title compound, C6H9NO4H2O [systematic name: (R,1R,2S)-rel--amino2-carboxycyclopropaneacetic acid monohydrate], crystallizes with two organic molecules and two water molecules in the asymmetric unit
P21 and the organic molecules are enantiomers, this is an example of a ‘false conglomerate’ with two molecules of opposite handedness in the asymmetric unit (r.m.s. overlay fit = 0.056 Å for one molecule and its inverted partner)
2-(20 -Carboxycyclopropyl)glycines CCG-I, CCG-III and CCG-IV (Fig. 1) are naturally occuring conformationally restricted analogs of glutamate isolated from Aesculus parviflora, Blighia sapida (Fowden, et al, 1969), Ephedra foeminea (Caveney & Starratt, 1994), and Ephedra altissima

Summary

Chemical context

2-(20 -Carboxycyclopropyl)glycines CCG-I, CCG-III and CCG-IV (Fig. 1) are naturally occuring conformationally restricted analogs of glutamate isolated from Aesculus parviflora, Blighia sapida (Fowden, et al, 1969), Ephedra foeminea (Caveney & Starratt, 1994), and Ephedra altissima Both enantiomers of CCG-II (Fig. 1) have been prepared in the laboratory (Shimamoto, et al, 1991) and all of the diastereomeric CCGs are useful tools for investigating the mechanism of glutamate function. The crystal structure of the title hydrate, ()-CCGIIIH2O, is reported

Structural commentary

Findings

Refinement