1,8-Diazabicyclo(5.4.0)undec-7-ene → 3-[3-(6-Methoxy-m-tolyl)-1,2-benzisothiazol-5-yl)-6-(trifluoromethyl)-2,4(1H,3H)-pyrimidinedione

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Reaction Steps

A mixture of ethyl 3-[(ethoxycarbonyl)amino]-4,4,4-trifluorocrotonate, (Z)-(2.04 g, 8 mmol), 5-amino-3-(6-methoxy-m-tolyl)-1,2-benzisothiazole (2.59 g, 9.6 mmol) and 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU, 1.46 g, 9.6 mmol) in xylene (15 mL) is heated at 110° C. for 6 hours, cooled, and quenched with ethyl acetate and water. The resultant mixture is extracted with ethyl acetate. The organic extracts are combined, washed with aqueous 2 N hydrochloric acid, dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo to obtain a foam. Flash chromatography of the foam using silica gel and a 3:7 ethyl acetate/hexanes solution gives the title product as a solid (2.5 g, 72% yield) which is identified by 1H and 19F NMR spectral analyses.

Provenance & Evidence