Synthesis of Novel Functionalized Derivatives of 5-Nitro-3,4-dihydropyrimidin-2(1H)-one by the Cyclocondensation of 1-Chlorobenzyl Isocyanates with N,S- and N,N-Nitroketeneacetals

Abstract

S y n t h e s i s o f 5 -N i t r o -3 , 4 -d i h y d r o p y r i m i d i n -2 ( 1 H ) -o n e D e r i v a t i v e sAbstract: The cyclocondensation of 1-chlorobenzyl isocyanates with S,N-and N,N-nitroketeneacetals has been employed to synthesize hitherto-unknown 6-methylthio-5-nitro-3,4-dihydropyrimidin-2(1H)-ones, 8-nitro-2,3,6,7-tetrahydroimidazo[1,2-c]pyrimidin-5(1H)-ones and 9-nitro-1,2,3,4,7,8-hexahydro-6H-pyrimido[1,6-a]pyrimidin-6(1H)-ones. Substitution of the methylthio group in 6-methylthio-5-nitro-3,4-dihydropyrimidin-2(1H)-ones provided 6-amino-5-nitro-3,4-dihydropyrimidin-2(1H)-ones, which exist in tautomeric equilibrium with 4-imino-5-nitro-3,4,5,6-tetrahydropyrimidin-2(1H)-ones. The compounds obtained, if boiled in dioxane in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), eliminate the nitro groups to give substituted 4-imino-3,4-dihydropyrimidin-2(1H)-ones.

Pyrrole- and Dihydropyrrole-Fused Neonicotinoids: Design, Synthesis, and Insecticidal Evaluation

“…α,β-Unsaturated enamine was reported as a typical 1,3-dipolar structure . It underwent various addition reactions with the conjugate fragment of the electron-donating amino and electron-withdrawing substitute . The reactions of α,β-unsaturated enamine with different functional groups afforded the corresponding five-, six-, and seven-membered cycloaddition products. − …”