The synthesis of 3‐[(dimethylamino)(2‐phenyl‐5‐oxo‐2‐oxazolinyl‐idene‐4)methyl]imidazo[1,2‐ x ]azines and related compounds, intermediates in the formation of azaaplysinopsin derivatives

4‐(2‐Bromo‐1‐dimethylaminoethylidene)‐2‐phenyl‐5(4 H )‐oxazolone ( 5 ) reacts with N,N ‐dimethyl‐ N'‐ heteroarylformamidines 7 to form imidazoazine derivatives 9 with the oxazolone ring connected through a conjugated double bond to the fused imidazole system at position 3. Compounds 9 were transformed with sodium methoxide in methanol into 2‐benzoylamino‐3‐dimethylamino‐3‐imidazoazinylpropenoates 10 , while by treatment with hydrochloric acid in methanol, 3‐(benzoylaminoacetyl)imidazoazines 12 were formed. The synthesis of compounds 9 represents a facile route to intermediates in the synthesis of azaaplysinopsin and related systems.