Reaction of 4,5‐diaminopyrimidine and ethyl acetoacetate: Synthesis and chemistry of isomeric dihydropyrimido[4,5‐ b ][1,4] diazepinones | Zendy

Israel Mervyn | Zendy; Tinter S. Karin | Zendy; Trites Dorothy H. | Zendy; Modest Edward J. | Zendy

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Reaction of 4,5‐diaminopyrimidine and ethyl acetoacetate: Synthesis and chemistry of isomeric dihydropyrimido[4,5‐ b ][1,4] diazepinones

Author(s) -

Israel Mervyn,

Tinter S. Karin,

Trites Dorothy H.,

Modest Edward J.

Publication year - 1970

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.5570070505

Subject(s) - chemistry , ethyl acetoacetate , moiety , yield (engineering) , medicinal chemistry , alkoxide , catalysis , bicyclic molecule , ring (chemistry) , stereochemistry , organic chemistry , materials science , metallurgy

Depending upon reaction conditions, 4,5‐diaminopyrimidine and acetoacetic ester gave a variety of condensation products, including the two isomeric dihydropyrimido[4,5‐ b ][1,4]‐diazepinones. Under conditions leading to bicyclic products, the formation of 1,5‐dihydro‐4‐methyl‐2 H ‐pyrimido[4,5‐ b ][1,4]diazepin‐2‐one ( 2 ) was strongly favored. The isomeric 3,5‐dihydro‐2‐methyl‐4 H ‐4‐one compound ( 4 ) was best obtained by cyclization of ethyl 3‐(4‐amino‐5‐pyrimidylamino)crotonate ( 3 ) under base catalysis. Thermal rearrangement of 2 and 4 proceeded, in each instance, with loss of the isopropenyl moiety and gave 8‐purinone. Compound 4 underwent ring contraction under the influence of alkoxide to yield a product which was shown to be the 7‐isopropenyl‐8‐purinone ( 6 ).

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