Methyl 4-[(Z)-amino(hydroxyimino)methyl]benzoate

Synthesis

General procedure for the synthesis of methyl 4-(N-hydroxyformamidinyl)benzoate (IV) from methyl 4-cyanobenzoate (III): methyl 4-cyanobenzoate (III) (2.50kg, 1wt) was dissolved in methanol (7.5L, 3vol) and diluted with methyl tert-butyl ether (9.3kg, 3.7wt). Aqueous hydroxylamine (50% solution; 1.23 kg, 0.5 wt, 1.2 eq.) was added slowly over about 0.5 h at 20-25 °C. The dosing line was flushed with methanol (1 kg, 0.4 wt) and the reaction was kept at 20-25 °C for about 12 hours. Upon completion of the reaction, the reaction mixture was cooled to 5±5°C and aged at this temperature for 3 hours. The product, methyl 4-(N'-hydroxyformamidinyl)benzoate (IV), was isolated by filtration, washed with methyl tert-butyl ether (2 x 5.5 kg, 2 x 2.2 wt) and dried under a stream of nitrogen for about 4 h to give the product (2.38 kg, 93% yield).

References

[1] Patent: WO2017/220446, 2017, A1. Location in patent: Page/Page column 26
[2] Journal of Labelled Compounds and Radiopharmaceuticals, 2012, vol. 55, # 2, p. 71 - 79
[3] Organic Letters, 2017, vol. 19, # 11, p. 2885 - 2888