21428-07-9Relevant academic research and scientific papers
Thermal reaction of cinnamic acid and of β-styrylphosphonic acid with urea
Vuano,Pieroni,Cabaleiro
, p. 318 - 320 (2007/10/03)
The thermal reaction of b-styrylphosphonic acid under experimental conditions similar to those applied to cinnamic acid and to methyl cinnamate to provide 6-phenyl-5,6-dihydrouracil, led to the formation of the novel 6-phenyl-5,6-dihydro-4-phosphorylamide-(1H,3H)-2-pyrimidinone.
β-UREIDO ACIDS AND DIHYDROURACILS. PART 15. EFFECT OF ALLYLIC STRAIN ON RING OPENING OF 1,6-DISUBSTITUTED DIHYDROURACILS
Koedjikov, Asen H.,Blagoeva, Iva B.,Pojarlieff, Ivan G.,Stankevic, Eva J.
, p. 1077 - 1082 (2007/10/02)
The rate profiles for the alkaline hydrolysis of some dihydrouracil and dihydro-orotic acid derivetives have been measured in order to assess the effect of allylic strain on the ring opening of 1,6-disubstituted dihydrouracils.The introduction of a 1-nitrogen-substituent in the 6-substituted compounds brings about a substantial decrease (40-500 times) in the observed rate constant which is second order in hydroxide ion (k1k3/k-1).The rate decreases of the addition step, k1, are moderate and in the range expected from the observed shifts in conformational equilibra towards the axial conformation which gives rise to a hindered transition state.The major contribution to the rate decreases from the ring-opening step, k3/k-1, and have been attributed to strains of the type associated with gem-dimethyl effect upon ring closure.
