Enantioselective synthesis of naturally occurring isoquinoline alkaloids: (S)-(−)-trolline and (R)-(+)-oleracein E

The highly efficient asymmetric syntheses of a pair of enantiomers, (S)-(−)-trolline and (R)-(+)-oleracein E, from commercially available 2-methyl-3-butyn-2-ol, benzaldehyde and 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline have been achieved in five steps with the catalytic enantioselective C1-alkynylation of 6,7-dimethoxy-3,4-dihydroisoquinoline as a key step, providing an efficient general approach for this type of naturally occurring chiral isoquinoline alkaloids.