Triphenylphosphine → 5-(2-Aminoethyl)thiophene-2-carboxamide

Participants

Reaction Steps

2-(2-Thienyl)ethyl p-toluenesulphonate (J.A.C.S. 95, 1973, 1247), acetyl chloride and aluminium chloride were reacted in methylene chloride to give 2-[(5-acetyl-2-thienyl)ethyl]p-toluenesulphonate (melting point 111°-112°, from ethanol). This was converted with sodium azide in dimethyl sulphoxide into 5-(2-azidoethyl)-2-thienyl methyl ketone. Oxidation with sodium hypobromite yielded 5-(2-azidoethyl)-2-thiophenecarboxylic acid of melting point 53°-55° C. Treatment of this acid with thionyl chloride gave the corresponding acid chloride which was reacted with ammonia to give 5-(2-azidoethyl)-2-thiophenecarboxamide (melting point 104°-105°, from ethanol). Reaction of this amide with triphenylphosphine and hydrolysis (J. Org. Chem. 40, 1975, 1659) gave 5-(2-aminoethyl)-2-thiophenecarboxamide of melting point 134°-136° (from acetonitrile).

Provenance & Evidence