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Synthesis and X-ray study of the 6-(N-pyrrolyl)purine and thymine derivatives of 1-aminocyclopropane-1-carboxylic acid

The novel purine and pyrimidine derivatives of 1-aminocyclopropane-1-carboxylic acid 1 and 2 were obtained by alkylation of 6-(N-pyrrolyl)purine and thymine with methyl 1-benzamido-2-chloromethylcyclopropanecarboxylate. X-ray crystal structure analysis shows that the cyclopropane rings in 1 and 2 posses Z-configurations. The cyclopropane ring atoms and attached atoms of the benzamido and methoxycarbonyl moiety of both molecules are disposed perpendicularly to each other. The carbonyl oxygen of the methoxycarbonyl moiety adopts in both compounds a synperiplanar conformation with respect to the midpoint of the distal bond of the cyclopropane ring. The torsion angles for the 1-aminocyclopropane-1-carboxylic acid residue in 1 and 2 correspond to a folded conformation, while the torsion angles define antiperiplanar conformation. Intermolecular hydrogen bonds connect the molecules of 1 into dimers. Each dimer is hydrogen-bonded with four ethanol molecules, thus forming discrete unit. On the contrary, intermolecular hydrogen bonds link the molecules of 2 generating three-dimensional network.

conformationally constrained amino acids ; hydrogen bonding ; purine and pyrimidine derivatives of 1-aminocyclopropane-1-carboxylic acid ; single crystal X-ray analysis

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