Ammonium Chloride → tert-Butyl 4-{4-[(E)-2-(naphthalen-1-yl)ethenyl]-1,3-thiazol-2-yl}piperidine-1-carboxylate

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Reaction Conditions

Reaction Steps

Under argon, diethyl 1-naphthylmethylphosphonate (1.88 g) is dissolved in tetrahydrofuran (20 ml) and cooled to 0° C. 757 mg of potassium tert-butoxide are added, whereupon the colour of the solution changes to dark-red. After a further 10 min of stirring, tert-butyl 4-(4-formyl-1,3-thiazol-2-yl)piperidine-1-carboxylate (1.00 g) is added. The mixture is stirred at 0° C. for 30 min and then warmed to room temperature. After a further 20 min, conc. ammonium chloride solution is added. The aqueous phase is separated off and extracted with ethyl acetate. The combined organic phases are dried over sodium sulphate and concentrated, and the residue is purified chromatographically. This gives tert-butyl 4-{4-[(E)-2-(naphthalen-1-yl)ethenyl]-1,3-thiazol-2-yl}piperidine-1-carboxylate (1.16 g) as the E isomer.

Provenance & Evidence