Reaction #1694

Reaction equation

1,4,5,6-tetrahydropyrimidine-5-carboxylic acid hydrochloride

oxalyl chloride

2-butyn-l-ol

→

5-(2-butynyloxycarbonyl)-1,4,5,6-tetrahydropyrimidine

Yield 61.0%

Solvents

water

benzene

Conditions

Workup

1. 1
   Temperatureheated
2. 2
   Temperatureunder reflux for 2.5 h
3. 3
   Otherevaporated to dryness in vacuo
4. 4
   Temperatureafter cooling
5. 5
   Otherto give an orange-yellow residue
6. 6
   workup.STIRRINGwas stirred at room temperature overnight
7. 7
   workup.STIRRINGAfter stirring overnight
8. 8
   Otherthe solvents were removed in vacuo
9. 9
   Otherto give a brownish residue
10. 10
    workup.STIRRINGstirred at room temperature for 2 h
11. 11
    Filtrationfiltered
12. 12
    OtherThe brown residue obtained on removal of the solvents in vacuo
13. 13
    Otherwas recrystallized (ethanol/ether)

Procedure

1,4,5,6-tetrahydropyrimidine-5-carboxylic acid hydrochloride (1 g, 6 mmol) was suspended in a solution of oxalyl chloride (1.5 mL, 17 mmol) in benzene (10 mL), heated with stirring under reflux for 2.5 h, and then evaporated to dryness in vacuo after cooling, to give an orange-yellow residue. A mixture of the acid chloride (04 g) and 2-butyn-l-ol (20 mL, excess) was stirred at room temperature overnight. After stirring overnight, the solvents were removed in vacuo to give a brownish residue. The residue was taken up in water (100 mL), stirred at room temperature for 2 h and filtered. The brown residue obtained on removal of the solvents in vacuo was recrystallized (ethanol/ether) to give a brown viscous oil (0.3 g, 61%) of 5-(2-butynyloxycarbonyl)-1,4,5,6-tetrahydropyrimidine as the hydrochloride salt. 1H NMR (D2O): δ 1.5 (t, 3H, CH3), 3.1 (m, 1H), 3.5 (d, 4H), 3.9 (q, 2H, OCH2), 7.9 (s, 1H, amidine-H). Anal. (C9H13N2O2Cl) C, H, N.

Source