A practical synthesis for the key intermediate of apixaban

Apixaban is a highly potent, selective, and efficacious inhibitor of blood coagulation factor Xa. A practical and efficient process has been developed for the preparation of the key intermediate of apixaban. Starting from inexpensive 4-chloronitrobenzene and piperidine, an eight-step procedure for the intermediate has been developed. In this case, sodium chlorite is used twice to oxidize the piperidine cycle to the corresponding lactam under a CO2 atmosphere, resulting in the construction of two lactams. Furthermore, most of these reactions are highly efficient and practical as they occur under mild conditions. Most of the intermediates can be obtained through simple slurry or recrystallization, and column chromatography purification is not necessary.