[N:1]1[CH:6]=[CH:5][CH:4]=[C:3]([C:7]2[S:8][CH:9]=[C:10]([C:12]([OH:14])=O)[N:11]=2)[CH:2]=1.CN(C)C.ClC(OCC(C)C)=O.[N-:27]=[N+:28]=[N-:29].[Na+]>ClCCl.C(Cl)(Cl)Cl.O>[N:1]1[CH:6]=[CH:5][CH:4]=[C:3]([C:7]2[S:8][CH:9]=[C:10]([C:12]([N:27]=[N+:28]=[N-:29])=[O:14])[N:11]=2)[CH:2]=1
A suspension of 2-(3-pyridyl)-thiazole-4-carboxylic acid (0.824 g, 4 mmol) in dichloromethane-chloroform (30 ml-15 ml) was treated with trimethylamine (0.75 ml, 0.5 g, 5 mmol) and then iso-butyl chloroformate (0.65 ml, 0.68 g, 5 mmol). After 1 h the mixture was evaporated to dryness and the residue suspended in THF (30 ml) and a solution of sodium azide (0.46 g, 7 mmol) in water (10 ml) was added. After 1 h, the mixture was concentrated (rotary evaporator) and partitioned between dichloromethane and brine. The organic extract was washed with half-saturated brine, dried, and evaporated. Trituration with petroleum ether, filtration, and drying in vacuo (CAUTION—no heating) afforded the title compounds as a brown solid (0.37 g, 40%).
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