New Synthetic Approach to C-30 Ethers, Esters, and Amines of Betulin Using the Mitsunobu Reaction and Biological Evaluation of the Products

A novel three-step synthetic approach for modification of betulin at position C-30 was developed starting from commercially available betulin diacetate. The scope of this procedure exceeds significantly the previously used methods while providing higher yields. The final Mitsunobu reaction was the pivotal step of the synthesis, and after optimization, 39 new derivatives─ethers, esters, and amines─were synthesized in good to high yields. All the novel compounds were tested for in vitro cytotoxic activity against six cancer cell lines and two noncancer cell lines. Compounds 30 and 37 show potent cytotoxicity against CCRF-CEM leukemia cells (IC50 around 5 μM). In addition, 37 exhibits broad activity across multiple cancer cell lines, suggesting a promising multitargeted anticancer activity. Both compounds impair DNA and RNA synthesis, with 37 strongly inhibiting transcription at high doses. Analysis of apoptosis induction shows a divergent profile in both compounds; while 30 promotes robust apoptosis, derivative 37 appears to engage alternative cell death pathways. Biosynthetic disruption emerges as a promising anticancer strategy, with 37 as a top lead candidate.