engleski

Spontaneous resolution of N-sulfonylpyrimidine compounds induced by chemical modifications

The title compounds belong to a novel series of pyrimidine nucleobase derivatives, some of which exhibit significant anticancer activity in vitro.[1] The crystal structures of 1-tosylthymine (1), 1-tosyluracil (2),  -naphthyl derivatives of thymine (3) and uracil (4) are presented. The conformational chirality was encountered in all compounds, as the consequence of the S-N single bond free rotation hindrance in solid state (atropisomerism).[2] The spontaneous resolution (á la Pasteur) of P and M conformational enantiomers occurred during the crystallization of 2 and 4, whereas their 5-methyl analogues, 1 and 3, crystallized as racemic mixtures. Moreover, spontaneous resolution in the case of 2 was accompanied by a formation of racemically twinned crystals regardless of the solvent used. Obviously, substituents at C-5 position of pyrimidine base as well as in -SO2-R group dictate the occurrence (or absence) of spontaneous resolution.

Conformational Chirality; Racemic Twinning; Pyrimidine Nucleobases

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