Improved syntheses of methyl (14E)- and (14Z)-dehydrocrepenynate: key intermediates in plant and fungal polyacetylene biosynthesis

Efficient syntheses of the (14E)- and (14Z)-isomers of methyl dehydrocrepenynate have been achieved. The key steps involve Pd-catalyzed cross-coupling reactions furnishing the CC double bonds between C14 and C15, followed by Wittig reactions to construct the (Z)-alkene at C9. High overall yields and stereoselectivities were achieved for both isomers.