Divergent synthesis of cytotoxic styryl lactones isolated from Polyalthia crassa. The first total synthesis of crassalactone B

The first total synthesis of (+)-crassalactone B (2) and a new syntheses of (+)-crassalactone C (3) has been achieved starting from d-glucose. The natural products 2 and 3 can be selectively accessed by changing the conditions for TBDPS cleavage in the final intermediate 16. The synthesized natural products were evaluated for their cytotoxic activity against a panel of human tumour cell lines.