The present disclosure provides processes for the preparation of a compound of formula:
which exhibits apoptosis signal-regulating kinase (“ASK1”) inhibitory activity and is thus useful in the treatment of diseases such as kidney disease, diabetic nephropathy and kidney fibrosis. The disclosure also provides compounds that are synthetic intermediates.
A direct synthetic approach to C-phosphanyl-N,N-dialkyl-N'-aryl(alkl)-formamidines was developed. It was shown that phosphorylation of the formamidines proceeds at the nitrogen atom affording N-phosphanylformamidinium salts. Upon deprotonation, these salts gave C-phosphanylformamidines via formation of carbenes followed by a 1,2-phosphorus shift. (C) 2013 Elsevier Ltd. All rights reserved.
Oszczapowicz, Janusz; Raczynska, Ewa, Polish Journal of Chemistry, 1983, vol. 57, # 4/5/6, p. 419 - 428