Oxalic Acid → (+/-)-1-[3-[[(3,4-Dihydro-2h-1-benzopyran-2-yl)-methyl]amino]propyl]tetrahydro-2(1h)-pyrimidinethione ethanedioate

Participants

Reaction Steps

A mixture of 3,4-dihydro-2H-1-benzopyran-2-carboxaldehyde (0.015 mol) and 1-(3-aminopropyl)tetrahydro-2(1H)-pyrimidinethione (0.01 mol) in methanol (150 ml) was hydrogenated for 2 days at room temperature (atmospheric pressure) with palladium on activated carbon (2 g) as a catalyst. After uptake of H2 (1 eq.), the catalyst was filtered off and the filtrate was evaporated. The residue was purified by column chromatography over silica gel (eluent: CH2Cl2 /(CH3OH/NH3) 95/5). The pure fractions were collected and the solvent was evaporated. The residue (0.3 g) was dissolved in ethanol (30 ml) and converted into the ethanedioic acid salt (1:1) with ethanedioic acid (0.3 g; 0.0124 mol). The precipitate was filtered off and dried (vacuum), yielding 0.3 g (7%) of (±)-1-[3-[[(3,4-dihydro-2H-1-benzopyran-2-yl)methyl]amino]propyl]tetrahydro-2(1H)-pyrimidinethione ethanedioate (1:1); mp. 217.6° C. (comp. 14).

Provenance & Evidence