THE REACTION OF ALLOXAN WITH INDOLE AND FURANES . STRUCTURE OF 5-INDOL-3-YL-5-HYDROXYPYRIMIDINE-2 , 4 , 6 ( 1 H , 3 H , 5 H )-TRIONE

The improved syntheses of 5-(indol-3-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (1), 5-(5-methylfuran-2-yl)-5-hydroxypyrimidine2,4,6(1H,3H,5H)-trione (2), 5-(5-N,N-dimethylhydrazonylfuran-2-yl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (3), 5-(4-N,N-dimethyl-aminophenyl)-5-hydroxypyrimidine-2,4,6(1H,3H,5H)-trione (4a), and 5-(4-N,N-diethylaminophenyl)-5-hydroxypyrimidine-2,4,6 (1H,3H,5H)-trione (4b) from alloxane in mild conditions were reported. The structure of 5-(indol-3-yl)-5-hydroxypyrimidine2,4,6(1H,3H,5H)-trione (1) has been determined by XRD study.


INTRODUCTION:
Recently, 5-(indol-3-yl)-5-hydroxypyrimidine-2,4,6(1H, 3H,5H)-trione 1 was used as the precursor for the synthesis of the range of inhibitors of HAT enzymes [1] .These compounds find utility in any number of therapeutic applications, including treatment of cancer.Compound 1 was synthesized by the reaction of alloxan with indole in boiling ethanol solution in the presence of HCl (Scheme 1). 1

Scheme 2.
Compound 2 can be regarded as a precursor in the synthesis of 5-(5-methylfuran-2-yl)hydantoin. 1 It can be supposed that alloxan derivatives 1, 2 may be synthesized in simpler route.This work was undertaken to simplification of syntheses of these compounds and derivatives and to study their structure.
The structure was solved by direct method using the SHELXTL program package [5] .At structure refinement limitations were made on bond lengths in solvent molecules (Csp 3 -Csp 3 1.54 Å, Csp 3 -O 1.44 Å).Positions of the hydrogen atoms were located from electron density difference maps and refined using the riding model with Uiso = 1.2Ueqv of the carrier atom.The hydrogen atoms taking part in the formation of hydrogen bonds were refined in isotropic approximation.
In the crystal molecules, А and В have a different supramolecular arrangement.Molecule A forms four intermolecular hydrogen bonds as the proton donor and three intermolecular hydrogen bonds as the proton acceptor.Molecule В forms four intermolecular hydrogen bonds as the proton donor and two intermolecular hydrogen bonds as the proton acceptor.

It
was found that 5-(5-methylfuran-2-yl)-5hydroxypyrimidine-2,4,6(1H,3H,5H)-trione 2 formed with high yield in alloxan hydrate reaction with 2-methylfurane in acetic acid solution at room temperature.In this reaction Sc(OTf)3 presence is not need.The structure of compound 2 has been proved by data of 1 H and 13 C NMR spectra and mass spectra.

Scheme 4.
The structures of compounds 3, 4a, and 4b are consistent with the data of 1 H and 13 C NMR spectra and mass spectra.Compound 3, 4a, and 4b may be regard as precursors for the synthesis of respective hydantoins.