Chemoenzymatic total synthesis of four stereoisomers of centrolobine.

Four stereoisomers of centrolobine, (3 R ,7 S )-(−)-centrolobine ( 1 ), (3 S ,7 S )-(−)- epi -centrolobine ( 2 ), (3 S ,7 R )-(+)-centrolobine ( 3 ), and (3 R ,7 R )-(+)- epi -centrolobine ( 4 ) have been achieved in an efficient manner in 24–28% overall yield over 9–10 linear steps starting from cheap and commercially available 4-methoxybenzaldehyde following chemoenzymatic protocol. The key features of this synthetic protocol are enzymatic resolution, cross-metathesis (CM), and our own developed tandem isomerization followed by C–O and C–C bond formation reaction. [ABSTRACT FROM AUTHOR]