1-[(2-Acetoxyethoxy)methyl]-3-ethoxycarbonylmethyl-6-azauracil

The product 2 was prepared via a direct condensation under solid-liquid phase transfer catalysis (S.L.P.T.C.) [1] conditions. To a solution of 0.02 mmole of tetraglyme in 4 ml of anhydrous THF, 0.11 mmole of potassium tert-butoxide is added. Then 0.1 mmole of the acyclonucleoside 1 [2] is added, the reaction mixture is stirred at room temperature for 15 min. The reaction mixture is cooled to 0°C and 0.11 mmole of alkylating agent in 2 ml of dry THF is added dropwise with stirring. When the addition is finished, the reaction mixture is stirred at 0°C for 30 min. The reaction mixture is then filtered and the filtrate is evaporated in vacuo to dryness. The residue is then chromatographed on a silica gel column and the expected acyclonucleoside 2 was isolated. Yield: 90 % (viscous and colourless).

Rf: 0.64 (CHCl₃ / MeOH, 9/1, V/V).

1H NMR (DMSO-d₆): 1.20 (t, 3H, CH₃CH₂); 2.00 (s, 3H, COOCH₃); 3.75 (m, 2H, OCH₂CH₂O); 4.10 (m,

2H, OCH₂CH₂O); 4.20 (q, 2H, CH₃CH₂); 4.75 (s, 2H, NCH₂); 5.25 (s, 2H, OCH₂N); 7.70 (s, 1H, H⁵).

UV (l max (nm), H₂O): 265.

MS (FAB, m/z): 316 [MH]⁺

Anal. calc. for C¹²H¹⁷N³O⁷: C 45.71, H 5.43, N 13.33; Found: C 45.69, H 5.40, N 13.40.