Trifluoroacetic acid → HCID 21268834, compound

Participants

Reaction Steps

A mixture of 9.15 g of 5,6-dihydro-4H-thieno[2,3-b]- thiopyran-5-carboxylic acid, 10 ml of diphenylphosphoryl azide and 6.5 ml of triethylamine in 200 ml of t-butanol is refluxed for 5 hours. After removal of the solvent in vacuo the residue is dissolved in ether and washed with 1N sodium hydroxide. After drying over magnesium sulfate the solvent is removed in vacuo to yield a mixture of N-t-butoxycarbonyl-5,6-dihydro-4H-thieno[2,3-b]-thiopyran-5-amine and N-t-butoxycarbonyl-2-t-butyl-5,6-dihydro-4H-thieno-[2,3-b]thiopyran-5-amine. The mixture is treated with 25 ml of trifluoroacetic acid and refluxed for 15 minutes. After removal of solvent the residue is treated with 40 ml of N-propyl iodide in 100 ml of toluene in the presence of 27 g of sodium carbonate in 150 ml of water. The resulting mixture is refluxed with stirring for 3 days. The solvent is removed from the organic layer and the residue is chromatographed on silica gel to afford 2-t-butyl-N,N-dipropyl-5,6-dihydro-4H-thieno[2,3-b]thiopyran-5-amine (hydrochloride salt, m.p. 227°-233°), and N,N-dipropyl-5,6-dihydro-4H-thieno[2,3-b]thiopyran-5-amine (hydrochloride salt, m.p. 163°-167°) of Example 2.

Provenance & Evidence