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Pyrazinoindoloquinone 6 was synthesized by alkylation of ethyl 4,7-dimethoxyindole-2-carboxylate (1), followed by cyclization of the N-bromoethyl derivative 2b in the presence of ammonia. Oxidative demethylation of 2b and of the oxopyrazinoindole 3 with silver(II) oxide furnished quinones 5b and 6. Reduction of 3 with lithium aluminium hydride in dioxane provided 4, which was oxidized to afford 7. Quinones 5b, 6, and 7 were then treated in situ with the thiazole o-quinodimethane 9 to afford regioisomeric mixtures of the tetracyclic

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The Diels-Alder reaction between a thiazole o-quinodimethane and 4,6-dichloroquinoline-5,8-dione gave 6-chloro-9-azaanthra[2,3-b]thiazole-5,10-dione as a single regioisomer. Its structure was assigned by 2D 1 H-13 C HMBC short-and long-range correlations. Measuring the spectra in CF 3 CO 2 D indicated that both nitrogen atoms of pyridine and thiazole rings are deuterated.

Pyrazine derivatives Pyrazine derivatives R 0550 Synthesis and Antiprotozoal Evaluation of Benzothiazolopyrroloquinoxalinones (V) and (VI), Analogues of KuanoniamineA. -(TAPIA*, R. A.; PRIETO, Y.; PAUTET, F.; WALCHSHOFER, N.; FILLION, H.; FENET, B.; SARCIRON, M.-E.;