p-Toluenesulfonic acid → HCID 178437839, Verbindung

Beteiligte Stoffe

Reaktionsschritte

A mixture of 1-cyclopentyl-3-ethyl-5-amino-1H-pyrazole-4-carboxamide (2.0 g, 9 mmol), anisaldehyde (2.45 g, 18 mmol), xylenes (50 ml) and p-toluenesulfonic acid (0.5 g) was refluxed for 32 hours. The reaction mixture was stripped to dryness, treated with ethanol (100 ml) and then again concentrated to dryness. The residue was treated with CHCl3 (100 ml) and 10% K2CO3 (100 ml), the layers were separated and the aqueous layer was extracted with chloroform (3×100 ml). The combined organic layers were concentrated to approximately 25 ml and then combined with silica gel (30 g). The preloaded silica was placed on a silica gel column and eluted with ether/hexanes (8/10) to ether (100%) to afford 1.25 g (41%) of 1-cyclopentyl-3-ethyl-6-(2-methoxyphenyl)-pyrazolo[3,4-d]pyrimidin-4-one, m.p. 135-136° C., after recrystallization from cyclohexane.

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