Chemical transformation of andrographolide

摘要

Tosylation of andrographolide 1, with p-TsCl pyridine furnishes compounds 3 and 4. The reaction of 1 with in situ generated nickel boride yields compounds 6 and 8. Monotosylation of 6 followed by reaction with NaI refluxing in acetone furnishes the iodide 13. But all attempts to generate an oxetane moiety in 13 corresponding to compound 2 failed.