Misuzu Ichiba

1,3-Dipolar cycloaddition of a thiazolo [5,4-d]pyrimidine 1-oxide to dimethyl acetylenedicarboxylate. New ring transformation to a pyrrolo-[3,2-d]pyrimidine via a pyrimido [4,5-b][1,4]thiazine

1,3-Dipolar cycloaddition of a thiazolo[5,4-d]-pyrimidine 1-oxide to dimethyl acetylenedicarboxylate resulted in the ring transformation of the thiazole moiety to give a pyrrolo [3,2-d] pyrimidine via a pyrimido [4,5-b]thiazine.

A new synthesis of alloxazines

The treatment of 6-anilino-4-hydroxy-5-p-nitro-phenylazo-2-phenylpyrimidines with 10% concentrated sulphuric acid in glacial acetic acid led to the formation of the corresponding 2-phenyl-2-deoxyalloxazines.