New Boron-Nitrogen Analogues of Uracil Derivatives [1]

The reaction o f N.N'-dim ethylurea with l,5-dim ethyl-2,4-bis-(dim ethylam ino)-l,5-diaza-2,4-dibora-3-oxacyclohexan-6-one (2) in the melt proceeds with condensation of the urea to yield two major products: the acid l,3,5-trim ethyl-2-hydroxy-l,3,5-triaza-2-boracyclohexa-4,5-dione (la); and a mixture of the methylammonium (4a) and dimethylammonium salt (4b) of the anion [{C H 3N («-C O N C H 3)2}2B ]_. Analogous products were obtained from the reaction of 2 with N,N',N"-triorganylbiurets. The 2-hydroxy derivatives of type 1 form 1:1 molar adducts with amines (3) of variable thermal stability. The anhydride of la was obtained as the bis(dimethylamine) adduct [CH3N (« -C 0 N C H 3)^B]^0-2 (CH 3)-,NH (6) from the reaction of [(CH 3)2N]2B O B [N (C H 3)2]2 with N,N',N"-trimethyibiuret.