Total synthesis of (+)-discodermolide

An enantioselective total synthesis of the marine natural product (+)-discodermolide has been accomplished utilizing a highly convergent and stereocontrolled strategy. The C1-C24 fragment was constructed via a palladium-mediated sp2-sp3 cross-coupling reaction between the C1-C14 vinyl iodide and the C15-C24 alkyl iodide subunits. The C1-C14 subunit was obtained using an acetate aldol reaction to construct the C6-C7 bond and install the C7 stereocenter with high levels of 1,5-anti stereoinduction. The key C13-C14 trisubstituted (Z)-olefin was prepared applying a novel hydrozirconation-cross-coupling methodology. The C1-C6, C7-C14 and C15-C24 subunits were synthesized using chiral silane-based asymmetric C-C bond construction methodology to introduce eight out of thirteen molecule's stereogenic centers. This synthesis illustrates the application of chiral crotylsilane bond construction methodology for the enantioselective synthesis of natural products and offers complementary approach to the aldol-based methodology.; A highly flexible and stereoselective protocol for the synthesis of functionalized (Z)- and (E)-trisubstituted alkenes has been developed. The key steps are hydrozirconation-iodination of (1-alkynyl)trimethylsilane followed by Negishi-type cross-coupling. The resultant (Z)-vinyl silane is iododesilylated and subjected to the second cross-coupling to give the trisubstituted olefin. Model studies aimed at the construction of C13-C14 trisubstituted olefin of (+)-discodermolide are described.