Drug Candidate for a New Indication

A Drug Candidate for a new indication (Original Lilly’s Patented Compound)

Processing problems:
  1. Total 12 steps with very low overall yield (<1%).
  2. Chiral resolution only had ~13% yield, 3 recrystallization.
  3. Tetrazole synthesis, lot of tar formed, difficult isolation with low yield.
  4. Wittig reaction, contracted to 3 companies without success.

Major Achievements & improvements by PGS:

  1. Steps 1-6. Overall improved from ~10% to 17.5%, cp >99%, one-single diastereomer.
  2. Chiral resolution improved from 13% to >42% with 99.5% ee in one-crystallization.
  3. Tetrazole synthesis, a 2-step process has been developed with overall 32% yield, cp >99%.
  4. Wittig reaction, the key problem has been resolved. A scalable lab process has been developed with ~75% isolated yield.The process has been scaled-up in the kg-lab with >5 kg initial SM successfully with cp >98%, ee >99.5%.
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