EP4370525A2 - A PROCESS FOR THE SYNTHESIS OF 4-((R)-2-{[6-((S)-3-METHOXY-PYRROLIDIN-1-YL)-2-PHENYL- PYRIMIDINE-4-CARBONYL]-AMINO}-3-PHOSPHONO-PROPIONYL)-PIPERAZINE-1 -CARBOXYLIC ACID BUTYL ESTER