Cyclopentanone → 1'-ethyl-6'-(pyridin-4-yl)-1'H-spiro [cyclopentane-1,2'-thieno[3,2-d]pyrimidin]-4'(3'H)-one

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Reaction Conditions

Reaction Steps

A mixture of 3-(ethylamino)-5-(pyridin-4-yl)thiophene-2-carboxamide (0.100 g, 0.400 mmol), cyclopentanone (2.0 mL), p-toluenesulfonic acid monohydrate (0.0095 g, 0.050 mmol) and acetic acid (2.0 mL) was stirred for 2 h at 100° C. in a sealed tube. The mixture was poured into sat. aqueous sodium hydrogen carbonate (150 mL). Extraction with ethyl acetate (100 mL, 50 mL), drying over magnesium sulfate, filtration and concentration at reduced pressure gave an oil. This oil was purified by column chromatography (Combiflash, 40 g silica gel, dichloromethane to ethyl acetate), then triturated with ethyl acetate, and the precipitate was collected by filtration to afford the title compound (0.0434 g, 28%) as a yellow solid:

Provenance & Evidence