Hydrochloric Acid → (R)-2-(4-bromophenyl)-2-cyclopropyl-N'-hydroxypropanimidamide

Participants

Reaction Conditions

Reaction Steps

To clean and dry reactor (vessel 1) is charged (R)-2-(4-bromophenyl)-2-cyclopropylpropanal oxime (8, 10.0 g, 24 wt %, 24.2 mmol, 1.00 equiv). To the solution is charged acetonitrile (30 mL). The resulting solution is cooled to an internal temperature of 10±5° C. To the solution is charged 3M hydrogen chloride solution in cyclopentyl methyl ether (0.80 mL, 2.4 mmol, 0.1 equiv). To a separate vessel (Vessel 2) is charged N-chlorosuccinimide (5.12 g, 36.3 mmol, 1.55 equiv) and acetonitrile (25 mL). The solution is agitated to form a slurry. To the batch at an internal temperature of 10±5° C. is charged the N-chlorosuccinimide solution (vessel 2) as a slurry at a rate to maintain the internal temperature NMT 25° C. An HPLC sample is removed and the HPLC conversion to the chloro-oxime is determined (Target >95 A % conversion). To the batch was charge ammonium hydroxide (28.7%, 7.39 g, 60.6 mmol, 2.50 equiv) at an internal temperature of 5±5° C. Note a small exotherm is observed due to the neutralization of the HCl. To the batch is charged water (10.0 g, 1.5 vols). The batch is agitated at an internal temperature of 20±5° C. for 15 h, or until HPLC analysis shows >95 A % conversion. To the batch is charged concentrated hydrogen chloride (37%, 12.0 g, 10.0 mL) and then heptane (34.2 g, 50 mL) and methyl tert-butyl ether (37.0 g, 50 mL). Agitation is initiated and to dissolve the remaining inorganic solids, water (25 g) is charged to the batch. The batch is agitated at an internal temperature of 20±5° C. for 10 min and the layers are allowed to settle. The bottom layer (ACN/water) is cut and the top (heptane/MTBE) layer is removed. The bottom ACN/water layer is charged back into the reactor. To the batch is charged isopropyl acetate (21.8 g, 25.0 mL) followed by 45 mL of ˜4N aqueous sodium hydroxide (prepared by dissolving 7.2 g sodium hydroxide in 45 mL water). The batch is agitated at an internal temperature of 20±5° C. for 20 min. The layers are allowed to settle and the aqueous layer is cut. To the batch is charged water (40.0 g, 40.0 mL) and the batch is agitated at an internal temperature of 20±5° C. for 20 min. The layers are allowed to settle and the aqueous layer is cut. To the batch is charged isopropanol (55.0 g, 70.0 mL) and the batch volume is adjusted to 20 mL via vacuum distillation (external temperature NMT 60° C.). The batch temperature is adjusted to an internal temperature of 15±5° C. and then the batch is seeded with crystalline (R)-2-(4-bromophenyl)-2-cyclopropyl-N′-hydroxypropanimidamide (9, 50 mg) and the batch is agitated at an internal temperature of 15±5° C. for 30 min to form a seed bed. To the batch is charged heptane (100 mL, 68.4 g) over a 1 h period at an internal temperature of 15±5° C. The batch is agitated at an internal temperature of 15±5° C. for 60 min. The solids are collected by filtration and the filtrate is used to rinse the reactor. The solids are suction dried for 3 h and mass 4.2 g (HPLC A % purity 97.8 A %, 61% yield) of (R)-2-(4-bromophenyl)-2-cyclopropyl-N′-hydroxypropanimidamide (9).

Provenance & Evidence