Hilbert—Johnson reaction

Both thermal and Hilbert-Johnson reactions occur quite readily in 2- and 4/6-alkoxyquinazolines. For example, distillation of 2,4-bis-/3-diethylaminoethoxyquinazoline in vacuo yields l,3-bis-/3-diethylaminoethylquinazolin-X4(l/J,3H )-dione (60JCS3546). A complicated example is furnished by heating a tetramethoxybipyrimidine with methyl iodide to give four separable products progressively (81AJC1157). 

The rearrangement of 2- or 4/6-alkoxypyrimidines, either by thermal means or by the Hilbert-Johnson reaction, also leads to iV-alkylpyrimidinones the former method is of little preparative value but the Hilbert-Johnson reactiop is quite important. The processes are outlined in Section 2.13.2.2.7/. 

Quinazoline, 2,4-bis(/3-diethylaminoethoxy)-Hilbert-Johnson reaction, 3, 93 Quinazoline, 2-chloro-4-(p-chlorophenylthio)-synthesis, 3, 137 Quinazoline, 6,8-dichloro-chlorosulfonation, 3, 76 Quinazoline, dihydrosynthesis, 3, 108, 124 Quinazoline, 2,4-dimethyl-Mannich reactions, 3, 78 Quinazoline, 4-ethoxy-1-oxide... 

Because activated 4-0-trimethylsilylated-2, 3, 5 -0-acyluridines such as 3 are also obtained as reactive intermediates in the Friedel-Crafts-catalyzed silyl-Hilbert-Johnson reaction [59, 59 a] of persilylated uracils or 6-azauracils such as 227 with sugars such as l-0-acetyl-2,3,5-tri-0-benzoyl-/9-D-ribofuranose 228 in the presence of SnCl4, treatment of the reactive intermediate 229 with a large excess of pyrrolidine neutralizes the SnCLi. used and aminates 229 to afford the protected 6-aza-cytidine 230, although in 57% yield only [49, 59] (Scheme 4.20). 

---