Synthesis of the C7-C23 fragment and its 18R,19S-diastereomer of iriomoteolide-1a has been accomplished from the C7-C12 allyl bromide, the C13-C16 vinyl iodide, and the C17-C23 alkyl iodide fragments. These fragments were assembled first by the B-alkyl Suzuki-Miyaura cross-coupling to give the C13-C23 intermediate. The latter, after being transformed into the C13 aldehyde, was coupled to the C7-C12 allyl bromide in the presence of indium powder in THF-H2O (1:1) at 70 ËC to the fully functionalized C7-C23 fragment with orthogonal protecting groups at C19 (PMB ether), and C9, C14, and C22 (TBS, TES, and TBS ethers, respectively). Formation of the characteristic six-membered C9/C13-hemiacetal ring has been demonstrated after global desilylation using pyridine-buffered HF.
Enantioselective total synthesis of the proposed structure of macrolide iriomoteolide-1b
作者:Zhengqing Ye、Tingyi Gao、Gang Zhao
DOI:10.1016/j.tet.2011.06.025
日期:2011.8
an enantioselective organocatalytic transfer hydrogenation of enal, a Julia–Kocienski olefination to establish the C15–C16 E-olefin moiety, a Kulinkovich reaction associated with cyclopropyl-allyl rearrangement to produce allyl stannane and ytterbium triflate and carboxylic acid promoted allylation between allyl stannane and aldehyde with tertiary alcohol at the α-position. The construction of macrolide