Hydrogen Sulfide → HCID 90913709, compound

Participants

Reaction Conditions

Reaction Steps

0.5 g (1.0 mmol) of the nitrile from Step E were dissolved in a mixture of 15 ml dry pyridine and 1.6 ml dry triethylamine. It was saturated with gaseous hydrogen sulfide, left at room temperature overnight, and poured into water. After three extractions with ethyl acetate the combined organic layers were dried over sodium sulfate and concentrated under reduced pressure. The residue was dissolved in 100 ml toluene, which was distilled off again in vacuo to remove traces of pyridine. To the remaining substance were added 5 ml acetone and 5 ml methyl iodide, and it was heated with reflux for 45 min, while a crystalline precipitate was formed. It was concentrated under reduced pressure, dissolved in 4 ml dry methanol, treated with 0.3 g (3.9 mmol) ammonium acetate and heated for 2 h at 60° C. The solvent was removed in vacuo, and the residue was stirred with ether. The solution was separated from the insoluble amidine, which was Boc-protected by dissolving in 10 ml of a 1:1 mixture of water and THF followed by addition of 0.9 g (6.5 mmol) potassium carbonate and 1.0 g (4.6 mmol) Boc2O and stirring for 1 hour at room temperature. It was diluted with water and extracted with ethyl acetate. The organic layer was dried over sodium sulfate and concentrated under reduced pressure, and the title compound was isolated by chromatography on silica gel with dichloromethane/ethanol 96:4.

Provenance & Evidence