Premium
Ring transformation of 6‐methyl‐3,4‐dihydro‐2 H ‐1,3‐oxazine‐2,4‐diones
Author(s) -
Kato Tetsuzo,
Izumi Uichiro,
Katagiri Nobuya
Publication year - 1978
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570150845
Subject(s) - chemistry , ethyl acetoacetate , hydrazine (antidepressant) , sodium hydride , sodium ethoxide , hydrate , medicinal chemistry , ethanol , tetrahydrofuran , sodium , ring (chemistry) , stereochemistry , organic chemistry , catalysis , chromatography , solvent
Ring transformation of 6‐methyl‐3,4‐dihydro‐2 H ‐1,3‐oxazine‐2,4‐dione (Ia) and its N ‐sub‐stituted derivatives, such as 3‐methyl (Ib), 3‐ethyl (Ic), and 3‐benzyl (Id) derivatives is described. Reaction of Ia with hydrazine hydrate gave 1‐amino‐6‐methyluracil (II), while Id reacted with hydrazine hydrate to give 3‐hydroxy‐5‐methylpyrazole (III). Reaction of Ia,b,d with ethyl acetoacetate in ethanol in the presence of sodium ethoxide afforded ethyl 3‐acetyl‐6‐hydroxy‐4‐methyl‐2(1 H ) pyridone‐5‐carboxylate derivatives (IVa,b,d). On the other hand, reaction of Ib,c,d with ethyl acetoacetate in tetrahydrofuran in the presence of sodium hydride did not give IV, but gave 3‐acetyl‐1‐alkyl‐5‐( N ‐alkylcarbamoyl)‐6‐hydroxy4‐methyl‐2(1 H ) pyridone (VIb,c,d). Mechanisms for the formation of compounds IV and VI are discussed.