Crotylation versus Propargylation: Two Routes for the Synthesis of the C13-C18 Fragment of the Antibiotic Branimycin

Felzmann, Wolfgang; Castagnolo, Daniele; Rosenbeiger, Daniela; Mulzer, Johann.  

Journal of Organic Chemistry  (2007),  72(6),  2182-2186. 

The C13−C18 fragment 3 of the novel antibiotic branimycin was prepared along two highly stereocontrolled routes. The first one uses a standard Roush crotylation protocol, whereas the second one proceeds via an allenyl silane propargylation with unexpected stereochemical consequences, which are discussed in detail.