Synthesis of Pyrimidine‐5‐carbaldehyde

Abstract

In the course of our studies on the nucleophilicity of the 5-position of substituted pyrimidines we obtained 4,6-dihydroxypyrimidine-5-carbaldehyde (2) by reaction in chloroform a t 0 to 20 "C of 4,6-dihydroxypyrimidine (prepared from malondiamide and formamide) with the reaction product of dirnethylformamide and phosgene 121. The formylation was exothermic with a yield of 93 % after 2 to 3 hr.Chlorination of the quaternary salt ( I ) with phosphorus oxychloride/dimethylaniline, or of ( I ) in dimethylformamide with phosgene/dimethylaniline (10 hr at 110 "C) and subsequent removal of the solvent, treatment of the residue with ice, and extraction with chloroform afforded 4,6-dichloropyrimidine-5-carbaldehyde (3) in 63 % yield [1,31.The formylation and chlorination can be carried out in one experiment : after the reaction with the dimethylformamidephosgene product the chloroform is removed and replaced by dimethylformamide, and phosgene is passed into the mixture for 10 hr at 110 "C. Hydrogenation of the chloro-aldehyde (3) with hydrogen and palladium-charcoal in methanol containing an excess of magnesium oxide (to remove the HCI) at room temperature and pressure and subsequent filtration, distillation of the methanol, and extraction of the residue with methylene chloride yielded the new compound pyrimidine-5-carbaldehyde, rn.p. 38-41 "C, in 79 % yield (40 % calculated on rnalondiamide).(2) H 1 NJ.C-CHO

1-Diazinylmethyl-2-nitromethylene- and 2-Nitroimino-imidazolidines as New Potential Insecticides

“…Pyrimidine derivative 14 having no nitrogen atom at 3-position on the aromatic ring was less active than the corresponding isomer 15. The pyrimidine derivatives (14, 15) that possessed the other nitrogen at 5-position were as active as the corresponding pyridine derivatives (6,7). We remarked on the favorable effect of some substituents at 4-position with iminyl nitrogen at 3-position on the arylgroup in the nitromethylene series.8) This effect of substituents was also observed in the diazine system.…”

“…While 2-chloro derivative (3) showed no activity, 4-chloro derivative (5) multiplied the activity of 2 by five times. In nicotinyl derivatives that possessed iminyl nitrogen at 3-position on the aromatic ring, an introduction of methyl or chloro moiety at 4-position on the aromatic ring multiplied the activity of 6 by five times or twentyfive times, respectively (6)(7)(8).…”

“…Pyridazine derivative (10) that possessed the other nitrogen at 2-position was less active than the most active pyridine derivative (8). Pyrazine derivatives (11,13) that possessed the other nitrogen at 6-position were as active as the corresponding pyridine derivatives (6,7). An introduction of a methyl substituent at 4-position on the aryl ring increased the activity, while an introduction of a methyl substituent at 2-position reduced the activity (11-13).…”