Synthese neuer 1,3-Oxazinone aus Cyanamiden und Chlorocarbonylketenen

Synthesis of new 1,3-Oxazinones from Chlorocarbonylketenes and Cyanamides Chlorocarbonylketenes 1a,b react with cyanamides 2a-i under mild conditions to form the 2-amino-1,3-oxazin-4-one derivatives 3a-i and 4 in mostly good yields. Treatment of compounds 3a,f with triethylamine in toluene in the presence of water or with triethylamine and benzylamine in toluene affords N-acylureas 5a,f, 2-amino-1,3-oxazin-4-ones 6, or malonamide 8, depending on the reaction conditions, whereas treatment of 3c with wet toluene leads to the formation of the 2-amino-1, 3-oxazin-6-one 7. Cycloaddition of biscyanmides 9a-c and chlorocarbonylketene 1a leads to the bis-oxazinone derivatives 10a-c in low to moderate yields; in the case of 10a, the monosubstituted product 11a is obtained as a side product.