15-Crown-5 → 2-(2,3,5,6-Tetrafluoro-4-pyridyl)-5-methyl-4-(3-methylbutyl)-1,2,5-thiadiazolidin-3-one 1,1-dioxide

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Reaction Steps

To a mixture of the sodium salt of 5-methyl-4-(3-methylbutyl)-1,2,5-thiadiazolidin-3-one 1,1-dioxide (1 g; 4.13 mmol, prepared by treatment with sodium methoxide), pentafluoropyridine (0.54 ml, 4.97 mmol), and 0.91 g (4.13 mmol) of 15-Crown-5 suspended in 30 ml of acetonitrile was refluxed for 17 hours. The mixture was cooled, concentrated in vacuo, and the residue extracted with methylene chloride, and the organic layer was washed with water (3x) and brine. After drying over sodium sulfate, the organic layer was concentrated in vacuo and a crude product was purified by flash chromatography (10% ethyl acetate in hexane) to afford 0.62 g (41%) of 2-(2,3,5,6-tetrafluoro-4-pyridyl)-5-methyl-4-(3-methylbutyl)-1,2,5-thiadiazolidin-3-one 1,1-dioxide (Formula I: R1 =(CH2)2CH(CH3)2 ; R2 =H; R3 =CH3), as a solid, m.p. 80.5°-81.5° C.

Provenance & Evidence