(E)-4-(dimethylamino)but-3-en-2-one

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Pyridinium tetrafluoroborate (2.21 g, 13.3 mmol) was added to a solution of (3E)-4-(dimethylamino)-3-buten-2-one (1.54 ml, 13.3 mmol) in 13.5 ml acetic anhydride/acetic acid (2:1). The resulting suspension was cooled to 0° C. and 3-dimethylaminoacroleine (1.33 ml, 13.3 mmol) was added over a period of 1 h under vigorous stirring and cooling with an ice bath receiving a red-brown precipitate. The cool reaction mixture was filtered and the remaining solid was washed with diethylether several times and dried under reduced pressure. The pentamethinium salt was obtained as orange crude product (2.69 g, 96%) and was used without any further purification. cooling with an ice bath The cool reaction mixture was filtered the remaining solid was washed with diethylether several times dried under reduced pressure

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Pyridinium tetrafluoroborate (2.21 g, 13.3 mmol) was added to a solution of (3E)-4-(dimethylamino)-3-buten-2-one (1.54 ml, 13.3 mmol) in 13.5 ml acetic anhydride/acetic acid (2:1). The resulting suspension was cooled to 0° C. and 3-dimethylaminoacroleine (1.33 ml, 13.3 mmol) was added over a period of 1 h under vigorous stirring and cooling with an ice bath receiving a red-brown precipitate. The cool reaction mixture was filtered and the remaining solid was washed with diethylether several times and dried under reduced pressure. The pentamethinium salt was obtained as orange crude product (2.69 g, 96%) and was used without any further purification. cooling with an ice bath The cool reaction mixture was filtered the remaining solid was washed with diethylether several times dried under reduced pressure

Conditions: temp:150.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: (3E)-4-(dimethylamino)but-3-en-2-one (255 mg, 2.25 mmol) and 2-hydrazinopyridine (369 mg, 3.38 mmol) were added to ethanol (3 ml). The reaction mixture was heated to 150° C. in the Biotage Initiator Series microwave reactor. After 30 minutes, the reaction mixture was cooled and concentrated. The residue was purified by column chromatography on silica gel, (ethyl acetate/isohexane gradient) to afford 2-(3-methyl-1H-pyrazol-1-yl)pyridine (faster eluting isomer) and 2-(5-methyl-1H-pyrazol-1-yl)pyridine (slower eluting isomer). the reaction mixture was cooled concentrated The residue was purified by column chromatography on silica gel, (ethyl acetate/isohexane gradient)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Pyridinium tetrafluoroborate (2.21 g, 13.3 mmol) was added to a solution of (3E)-4-(dimethylamino)-3-buten-2-one (1.54 ml, 13.3 mmol) in 13.5 ml acetic anhydride/acetic acid (2:1). The resulting suspension was cooled to 0° C. and 3-dimethylaminoacroleine (1.33 ml, 13.3 mmol) was added over a period of 1 h under vigorous stirring and cooling with an ice bath receiving a red-brown precipitate. The cool reaction mixture was filtered and the remaining solid was washed with diethylether several times and dried under reduced pressure. The pentamethinium salt was obtained as orange crude product (2.69 g, 96%) and was used without any further purification. cooling with an ice bath The cool reaction mixture was filtered the remaining solid was washed with diethylether several times dried under reduced pressure