Water → HCID 19771711, compound

Participants

Reaction Conditions

Reaction Steps

A solution of tetrahydrothiopyran-4-one (20.0 g), morpholine (15.0 g) and p-toluenesulphonic acid (200 mg) in toluene (100 ml) was heated under reflux for 24 hours with azeotropic removal of water. Volatile material was removed by evaporation and the residue was heated with 5-(1-hydroxypropylidene)-2,2-dimethyl-1,3-dioxane-4,6-dione (68 g) at 120° C. for 3 hours. The mixture was dissolved in dichloromethane (300 ml) and the solution was washed with 2M sodium hydroxide solution (2×100 ml), water (2×100 ml) and saturated sodium chloride solution (100 ml). The organic phase was then dried (MgSO4) and volatile material was removed by evaporation. The residue was purified by flash chromatography, eluting with ethyl acetate/hexane (1:1 v/v), to give 7,8-dihydro-2-ethyl-thiopyrano[4,3-b]pyran-4(5H)-one (B) (9.2 g), as an oil; NMR (CDCl3) 1.2(t, 3H). 2.55(q, 2H), 2.8-2.9(m, 4H), 3.55(s, 2H), 6.1(s, 1H).

Provenance & Evidence