A concise, flexible, and high-yielding synthesis of the macrocyclic compound 4 is outlined which served as a key intermediate in a previous total synthesis of the antitumor active alkaloid roseophilin 1. The key steps of this approach consist of a Pd(0)-catalyzed reaction of vinyloxirane 6 with sulfone 7 and in a subsequent ring closing metathesis (RCM) reaction for the formation of the 13-membered ring catalyzed by the ruthenium carbene Cl₂(PCy₃)₂Ru=CHCH=CPh₂ introduced by Grubbs. Moreover, nitrile ylide cycloaddition reactions are used for the preparation of roseophilin side chain mimics. Finally, the synthesis of various chromophore analogues of 1 is reported, including deschloro-desmethoxyroseophilin 12 which is the most elaborate derivative of this complex target reported so far

The first total synthesis of cristatic acid 1, an antibiotic endowed with considerable activity against Gram-positive bacteria, hemolytic properties, and significant cytotoxicity, is described. Key to success are the formation of its 2,4-disubstituted furan moiety via a palladium-catalyzed alkylation of vinylepoxide 10 derived from sulfonium salt 8 and the use of SEM ethers as the protecting groups for the phenolic OH functions

No abstract

No abstract

A new catalytic enantioselective method has been developed for the allylation of imines 1 by substituted allylstannanes 2 with chiral zirconium catalysts prepared from zirconium alkoxides and 1,1′‐bi‐2‐naphthol (BINOL) derivatives. The allylated products 3 were obtained in high yields and with excellent enantiomeric excesses. The basic concept of the reaction provides a convenient entry to various chiral building blocks.