Synthesis of 4,4-Disubstituted 3,4-Dihydropyrimidin-2(1<i>H</i>)-ones and -thiones, the Corresponding Products of Biginelli Reaction Using Ketone, and Their Antiproliferative Effect on HL-60 Cells

Abstract

An efficient synthetic method for novel 4,4-disubstituted 3,4-dihydropyrimidin-2(1H)-ones 5 and -thiones 6 was developed. The cyclocondensation reaction of O-methylisourea hemisulfate salt 11 with 8 gives a tautomeric mixture of dihydropyrimidines 12 and 13 following acidic hydrolysis of the cyclized products to produce 5 in high yields. Thionation reaction of 5 at the 2-position smoothly proceeds to give 2-thioxo derivatives 6. These compounds 5 and 6, corresponding to the products of a Biginelli-type reaction using urea or thiourea, a ketone and a 1,3-dicarbonyl compound, have long been inaccessible and hitherto unavailable for medicinal chemistry. These methods are invaluable for the synthesis of 5 and 6, which have been inaccessible by conventional methods. Therefore, the synthetic methods established in this study will expand the molecular diversity of their related derivatives. These compounds were also assessed for their antiproliferative effect on a human promyelocytic leukemia cell line, HL-60. Treatment of 10 µM 6b and 6d showed high inhibitory activity similarly to 1 µM all-trans retinoic acid (ATRA), indicating that the 2-thioxo group and length of two alkyl substituents at the 4-position are strongly related to activity. Key words 4,4-disubstituted 3,4-dihydropyrimidin-2(1H)-one; 4,4-disubstituted 3,4-dihydropyrimidin-2(1H)-thione; 2-(gem-disubstituted methylene)-3-oxoester; Biginelli reaction; antiproliferative effect; tautomer

Cytotoxic effects of novel 2-methylthio dihydropyrimidines on human acute myeloid leukemia cell lines

“…The structure of DP01-DP11 is introduced 6-methyl or phenyl group on 2-methythio DP, on the other hand, that of P12-DP19 is 6-oxo one. Our previous studies demonstrated that 2-oxo DPs do not induce cytotoxic effects against HL-60 cells [18,20]. Therefore, all these ndings suggest that the introduction of the oxo-group into the structure of DP results in the reduction of cytotoxicity against NB4 and HL-60 cells.…”

“…Cytotoxicity of 2-methylthio DPs against NB4 or HL-60 cells was measured by XTT assay as described previously [20] or WST-8 assay kit according to the manufacturer's instructions. Brie y, XTT/PMS mixed solution (1.5 mM XTT and 0.025 mM PMS in PBS) or WST-8 solution of a quarter or a tenth of the medium in well was added followed by incubation at 37 °C for 4 h or 1 h. Next, the plate was mixed on a mechanical plate shaker, and absorbance at 450 nm was measured with a microplate reader, SpectraMax Pro M5 e (Molecular Devices, USA).…”

“…Our previous studies have focused on the anticancer activity and safety of natural products including food, traditional herb, kampo, and their phytochemicals [13][14][15][16][17]. Recently, our previous studies also have demonstrated that 6-unsubstituted 2-thioxo-, 2-oxo-, and 2-amino DPs, and 4,4-disubstituted 3,4-dihydropyrimidine-2(1H)-ones and -thiones induced cytotoxicity against a human promyelocytic leukemia cell line, HL-60 [18][19][20], suggesting that DPs might be candidates for anticancer compounds. But the detailed studies of whether 2-methylthio DPs induce cell growth inhibition, cell differentiation, and cell death have not been elucidated.…”

Synthesis of 3,4-Dihydropyrimidin(thio)one Containing Scaffold: Biginelli-like Reactions

“…The process makes use of 2-aminobenzothiazole 152 as a nitrogen source, dimedone 33, and aromatic aldehydes 2 (Scheme 76) [156]. Unlike aldehydes, ketones are not reactive enough to engage in the classical Biginelli reaction acting as electrophiles and they always react as a nucleophile via enolization; however, very recently, Nishimura et al prepared the key intermediate 171 by using TiCl4 and pyridine in a Knoevenagel-type condensation (Scheme 77) [157]. Thus, the cyclocondensation reaction of this compound 171 with O-methylisourea hemisulfate salt 5 gave a tautomeric mixture of dihydropyrimidines 172 and 173; this mixture was hydrolyzed to produce 4,4-disubstituted 3,4-dihydropyrimidin-2(1H)-ones 174 in high yields; these products had been inaccessible and hitherto unavailable for medicinal chemistry and were assessed for their antiproliferative effect on a human promyelocytic leukemia cell line, HL-60.…”

“…and pyridine in a Knoevenagel-type condensation (Scheme 77) [157]. Thus, the cyclocondensation reaction of this compound 171 with O-methylisourea hemisulfate salt 5 gave a tautomeric mixture of dihydropyrimidines 172 and 173; this mixture was hydrolyzed to produce 4,4-disubstituted 3,4-dihydropyrimidin-2(1H)-ones 174 in high yields; these products had been inaccessible and hitherto unavailable for medicinal chemistry and were assessed for their antiproliferative effect on a human promyelocytic leukemia cell line, HL-60.…”