2-Thiophenecarboxaldehyde → 5-(Thiophen-2-yl)-1,3-oxazole

Reaction equation

C1(C)C=CC(S([CH2:10][N+:11]#[C-:12])(=O)=O)=CC=1.[S:14]1[CH:18]=[CH:17][CH:16]=[C:15]1[CH:19]=[O:20].C(=O)([O-])[O-].[K+].[K+]>CO>[S:14]1[CH:18]=[CH:17][CH:16]=[C:15]1[C:19]1[O:20][CH:12]=[N:11][CH:10]=1

Participants

Procedure

To a solution of p-toluenesulfonylmethyl isocyanide (3.0 g, 15.36 mmol) and Thiophene-2-carboxaldehyde (1.72 g, 15.36 mmol) in methanol (45 mL) under N2 is added potassium carbonate (2.12 g, 15.36 mmol). The mixture is heated to reflux for 5 hr, then cooled and concentrated in vacuum (cold water bath). The residue is partitioned between ether (100 mL) and water (100 mL). The organic layer is washed with water (100 mL), dried over magnesium sulfate and then concentrated in vacuum. The residue is purified over 35 g silica gel, eluted with ethyl acetate: heptane (1:5) to afford 5-thiophen-2-yl-oxazole (0.852 g, 37%).