Syntheses and cytotoxicity of (R)- and (S)-7-methoxycryptopleurine

Two efficient protocols are described for the transformation of a key chiral homoallyllic sulfinamine intermediate in four steps into enantioenriched 7-methoxycryptopleurine. While one of the protocols relied on a rhodium catalyzed linear hydroformylation process, the alternative approach was based on a ring-closing metathesis from the corresponding N-allyl-sulfinamine. The cytotoxic evaluation of both enantiomers of the target compound demonstrated that the (R)-compound is much more potent than its antipode against the four cancer cell lines examined.