The possible synthesis of (3-alkoxycarbonylmethyl-4-oxo-3,4-dihydro-2-pyrimidinylsulfanyl) acetate esters

Abstract

Compounds with alkoxycarbonylmethyl groups in adjacent positions in a pyrimidine ring can be used as synthons in the preparation of polycyclic heterosystems. Our previous attempt [1] to synthesize pyrimidine derivatives having S-and N-alkoxycarbonylmethyl groups respectively in positions 2 and 3 of the ring by alkylation of the corresponding 4-hydroxy-2-mercaptopyrimidine or methyl 4-hydroxy-2-methoxycarbonylmethylsulfanylacetate with methyl bromoacetate were unsuccessful since only the S-or N-dialkylation product was formed. Continuing our work in this area we have found that compounds 2a,b can be prepared by treating the corresponding 2-methylsulfanyl derivatives 1a,b with methyl or ethyl mercaptoacetate in the presence of base: N N O Me SMe N N O Me CH 2 COOR 2 R 1 HSCH 2 COOR 2 R 1 CH 2 COOR 2 SCH 2 COOR 2 1a,b 2a,b 1,2 a R 1 = Br, R 2 = Me; b R 1 = NO 2 , R 2 = EtIt should be noted that compound 2a was obtained by refluxing compound 1a in tert-butanol with methyl mercaptoacetate in the presence of potassium tert-butylate whereas treatment of compound 1b with ethyl mercaptoacetate under the same conditions gave a complex mixture of products, from which pure compounds could not be separated. Compound 2b was prepared with the use of triethylamine as base.IR spectra were obtained on a Perkin-Elmer BX FT-IR spectrometer for KBr tablets. 1 H NMR and 13 C NMR spectra were taken on a Varian Unity Inova instrument (300 and 75 MHz respectively) using CDCl 3 relative to TMS.Compound 1a was prepared as described before [2].