Solid-Phase Synthesis of 5-Isoxazol-4-yl-[1,2,4]oxadiazoles
作者:Chao Quan、Mark Kurth
DOI:10.1021/jo0352124
日期:2004.3.1
A library of isoxazole and 1,2,4-oxadiazole-containing diheterocyclic compounds has been prepared. Our strategy was explored in solution phase first as follows. PMB-protected 3-butyn-2-ol was deprotonated with nBuLi, acylated with methyl chloroformate, and then employed in a nitrile oxide 1,3-dipolar cycloaddition (benzaldehyde oxime in the presence of bleach) to afford the isoxazole-substituted carboxylic acid methyl ester. Ester saponification with aqueous NaOH followed by a two-step condensation with benzamidoxime gave the final isoxazole-oxadiazole diheterocyclic product in good yield. With some modifications, we next explored this chemistry on Wang resin, which led to 18 final products that were cleaved from polymer beads with 50% TFA in dichloromethane.
Transition-Metal-Free Synthesis of Electron Rich 1,3-Dienes via Base Promoted Isomerization of Propargylic Ethers
作者:Chunxiang Liu、Guogang Deng、Xin Li、Yiren Xu、Kaili Yu、Wen Chen、Hongbin Zhang、Xiaodong Yang
DOI:10.1002/ejoc.201901743
日期:2020.1.31
An efficient and broadly applicable method for the construction of functionalized electron rich 1,3‐dienes through a base promoted isomerization reaction of propargylic ethers is presented. This process features easy handling reaction conditions, transition‐metal‐free isomerization, high isolated yields, and most of all, it could be used for late stage modification of natural products.
Total Synthesis of the Enantiomer of the Furanocembrane Rubifolide
作者:James A. Marshall、Clark A. Sehon
DOI:10.1021/jo970360d
日期:1997.6.1
The total synthesis of 57, the enantiomer of the marine furanocembrane rubifolide (3), is described starting from (S)-(-)-perillyl alcohol (5). The successful route proceeded by oxidative cleavage of 5 to esteraldehyde 30 which was protected, reduced, and homologated to the acetylene 34, the left-hand segment of the synthetic target. Addition to the right-hand aldehyde 39 afforded alcohol 40. The carbonate