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-configuration. 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 Phi and psi for the 1-aminocyclopropane-1-carboxylic acid residue in 1 and 2 correspond to a folded conformation, while the torsion angles omega 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.

Synthesis and antitumor activities of novel pyrimidine derivatives of 2,3-O,O-dibenzyl-6-deoxy-L-ascorbic acid and 4,5-didehydro-5,6- dideoxy-L-ascorbic acid

The new pyrimidine derivatives of 2,3-O, O-dibenzyl-6-deoxy-L-ascorbic acid (8-10) were synthesized by condensation of uracil and its 5-fluoro- and 5-trifluoromethyl-substituted derivatives with 4-(5,6-epoxypropyl)-2, 3-O,O-dibenzyl-L-ascorbic acid (7), while pyrimidine derivatives of 4,5-didehydro-5,6-dideoxy-L-ascorbic acid (14-17) with free C-2' and C-3' hydroxy groups in the lactone ring were obtained by debenzylation of 11-13 with boron trichloride. Z-Configuration of the C4'=C5' double bond and position of the benzyl group in the lactone ring of 14 were deduced from their (1)H and (13)C NMR spectra and connectivities in COSY, ROESY, and HMBC spectra. The exact stereostructure of 13 was confirmed by its X-ray crystal structure analysis. Of all the compounds in the series, compound 16 containing a 5-fluoro-substituted uracil ring showed the most significant antitumor activities against murine leukemia L1210/0 (IC(50) = 1.4 microg/mL), murine mammary carcinoma FM3A/0 (IC(50) = 0.78 microg/mL), and, to a lesser extent, human T-lymphocyte cells Molt4/C8 (IC(50) = 31.8 microg/mL) and CEM/0 cell lines (IC(50) = 20.9 microg/mL).

Novel pyrimidine and purine derivatives of L-ascorbic acid: synthesis and biological evaluation

The novel pyrimidine derivatives 1-6 of 2,3-dibenzyl-4,5-didehydro-5, 6-dideoxy-L-ascorbic acid were synthesized by the condensation of pyrimidine bases with 5,6-diacetyl-2,3-dibenzyl-L-ascorbic acid (DDA). Both N-9 (7) and N-7 (8) regioisomers were obtained in the reaction of 6-chloropurine with 5-acetyl-6-bromo-2, 3-dibenzyl-L-ascorbic acid (ABDA), while the reaction of 6-(N-pyrrolyl)purine with ABDA afforded exclusively the N-9 isomer 9. Structures of all newly prepared compounds were deduced from the chemical shifts in (1)H and (13)C NMR spectra, as well as connectivities in 2D homo- and heteronuclear correlation spectra. An unambiguous proof of the structure and conformation of 7 was obtained by X-ray crystallographic analysis. Compounds 1-9 were found to exert cytostatic activities against malignant cell lines: pancreatic carcinoma (MiaPaCa2), breast carcinoma (MCF7), cervical carcinoma (HeLa), laryngeal carcinoma (Hep2), murine leukemia (L1210/0), murine mammary carcinoma (FM3A), and human T-lymphocytes (Molt4/C8 and CEM/0), as well as antiviral activities against varicella-zoster virus (TK(+)VZV and TK(-)VZV) and cytomegalovirus (CMV). The compound 6 containing a trifluoromethyl-substituted uracil ring exhibited marked antitumor activity. The N-7-substituted purine regioisomer 8 had greater inhibitory effects on the murine L1210/0 and human CEM/0 cell lines than the N-9 isomer 7. Compound 9 with the 6-purine-substituted pyrrolo moiety had a more pronounced selective cytostatic activity against human (Molt4/C8 and CEM/0) cell lines than murine (L1210/0 and FM3A/0) and human (MiaPaCa2, MCF7, HeLa, and Hep2) tumor cell lines and normal fibroblasts (Hef522). The compound 6 exhibited the most potent antiviral activities against TK(+)VZV, TK(-)VZV, and CMV, albeit at concentrations that were only slightly lower than the cytotoxic concentrations.