(100 ml), urea (24 g, 0.4 mol) was added, and the mixture was boiled for 14 h. Conc. HCl (50 ml) was carefully
added to the boiling mixture and it was boiled for another 20 min, then water (150 ml) was added. The crystals
that precipitated upon cooling were filtered out and washed with water. In order to remove N-substituted ureas,
the crystals were dissolved with heating in a 10% sodium hydroxide solution (150 ml), cooled down, and
filtered. The filtrate was heated to boiling, acetic acid (35 ml) was carefully poured in, and then conc. HCl was
added to pH 0-1 and it was boiled for 10 min. The crystals of dihydropyrimidinedione 8 that precipitated upon
cooling were filtered out and washed with water.
1-(4-(Phenoxyphenyl)dihydro-4-(1H,3H)-pyrimidinone-2-thione (9) was obtained as for compound 8,
except that potassium thiocyanate (29.1 g, 0.3 mol) was used instead of urea.
3-Benzoyl-1-(4-phenoxyphenyl)dihydro-2,4-(1H,3H)-pyrimidinone (10). Dihydropyrimidinedione 8
(2.82 g, 0.01 mol), benzoyl chloride (2.08 g, 0.02 mol) in pyrimidine (10 ml) were boiled for 2 h, the mixture
was diluted with water (1:10), the precipitated mass was removed, washed three times with water, and
crystallized from ethanol.
5-Methyl(or 6-methyl)-1-(4-phenoxyphenyl)dihydro-2,4-(1H,3H)-pyrimidinediones (13, 17). The
corresponding β-alanine or its hydrochloride 3, 4 (0.05 mol), urea (6.0 g, 0.01 mol), and acetic acid (25 ml) were
boiled for 14 h; conc. HCl (15 ml) was added, and it was boiled for another 15 min. Then the mixture was
diluted with water (50 ml) and cooled down; the precipitated crystals of dihydropyrimidinediones 13, 17 were
filtered out and washed with water. In order to remove the N-substituted ureas, the crystals were dissolved with
heating in a 10% sodium hydroxide solution (30 ml), cooled down, and filtered. The filtrate was heated to
boiling, acetic acid (15 ml) was carefully poured in, and then conc. HCl (15 ml) was added and it was boiled for
5-10 min. The crystals of dihydropyrimidinediones 13, 17 that precipitated upon cooling were filtered out and
washed with water.
5-Methyl(or 6-methyl)-1-(4-phenoxyphenyl)-4-(1H,3H)-dihydropyrimidinedione-2-thiones (14, 18)
were obtained from the corresponding β-alanine or its hydrochloride 3, 4 (0.05 mol) and potassium thiocyanate
(5.8 g, 0.06 mol), as for compounds 13, 17.
4-Carboxy-1-(4-phenoxyphenyl)-2-pyrrolidinone (19). Compound 1 (37.0 g, 0.2 mol) and itaconic
acid (32.5 g, 0.25 mol) in 50% acetic acid (250 ml) were boiled for 5 h, the mixture was diluted with water
(250 ml) and cooled down, the precipitated crystals were filtered out and washed with water. They were purified
twice by dissolving the crystals obtained in 50% NaOH (250 ml), filtering out the unreacted amine, and
acidifying the filtrate with 10% HCl to pH 1.
4-Methoxycarbonyl-1-(4-phenoxyphenyl)-2-pyrrolidinone (20).
A
mixture of 4-carboxy-2-
pyrrolidinone 19 (8.91 g, 0.03 mol), methanol (150 ml), and conc. H2SO4 (1 ml) was boiled for 8 h. The liquid
fractions were distilled off under vacuum. A 5% Na2CO3 solution (150 ml) was added to the residue and the
mixture was heated to boiling. The crystals of compound 20 that precipitated after cooling were filtered out,
washed with water, and crystallized from ethanol.
Hydrazide of 4-Carboxy-1-(4-phenoxyphenyl)-2-pyrrolidinone (21). The methyl ester 20 (6.22 g,
0.02 mol) in a mixture of hydrazine hydrate (4.0 g, 0.08 mol) and 2-propanol (50 ml) was boiled for 30 min. The
crystals of hydrazide 21 that precipitated upon cooling were filtered out and washed with 2-propanol and then
ether.
Arylidene Hydrazides of 4-Carboxy-1-(4-phenoxyphenyl)-2-pyrrolidinone (22, 23). Hydrazide 21
(1.55 g, 0.005 mol) and the corresponding aldehyde (0.01 mol) were boiled for 2 h in 2-propanol (30 ml) and
then cooled down. The precipitated crystals were filtered out and washed with 2-propanol and then ether.
2-{[2-Oxo-4-pyrrolidinyl-1-(4-phenoxyphenyl)]}benzimidazole (24). A mixture of 4-carboxy-2-
pyrrolidinone 19 (1.94 g, 0.05 mol) and o-phenylenediamine (0.76 g, 0.07 mol) was heated for 3 h at 170°C.
Then the temperature was raised to 210-220°C, and heating was continued for another 30 min. A 5% NaOH
solution (50 ml) was added to the remaining reaction mass; this was boiled for 5 min and allowed to stand at
20°C for 30 min. The dark-brown crystals formed were filtered out, washed with water, dried, and crystallized
from toluene.
786
Mickevicius
