Synthesis of novel 3'-trifluoromethyl taxoids through effective kinetic resolution of racemic 4-CF3-beta-lactams with baccatins.

The coupling of racemic 1-tBoc-4-CF3-beta-lactams with various C-10 modified baccatins has resulted in CF3-taxoids with diastereoselectivities ranging from 9:1 to one single isomer. The observed high diastereoselectivity is ascribed to the highly efficient enantiomer-differentiation by the enantiopure lithium alkoxide of a baccatin III in the coupling reaction with a racemic 1-tBoc-beta-lactam. These novel CF3-taxoids have also been shown to exhibit significant increases in activity against various cancer cell lines compared to either paclitaxel or docetaxel. In addition, the first asymmetric synthesis of a CF3-beta-lactam via chiral ester enolate-imine cyclocondensation was performed with 50% enantioselectivity.