or Ph3P - CCl4] of triketides bearing optically active functional groups to the corresponding γ-pyrones provided determination of the absolute configurations of ilikonapyrone and peroniatriols I and II isolated from the marine molluscs Onchidium verruculatum and Peronia peronii.
Neighboring-groupparticipation of an acyl protecting group efficiently promotes the Bronsted acid-catalyzed dehydrative cyclization of 1,3,5-triketones to gamma-pyrones, whereas a bulky silyloxy group in the beta-position retards the cyclization. This reaction provides an efficient synthetic route for a common intermediate for the synthesis of gamma-pyrone-containing bioactive natural products.
Studies in Marine Polypropionate Synthesis: Total Synthesis of (−)-Baconipyrone C
作者:Ian Paterson、David Yu-Kai Chen、José Luis Aceña、Alison S. Franklin
DOI:10.1021/ol000027n
日期:2000.6.1
[reaction--see text] An asymmetric totalsynthesis of the unusual siphonariid metabolite, (-)-baconipyrone C (3), is described. Key steps included a tin(II)-mediated aldol coupling for the preparation of the carboxylic acid 17 and two different boron-mediated aldol additions leading to alcohol 8. Ester formation using modified Yamaguchi conditions gave 24, leading on PMB deprotection to (-)-baconipyrone C.
[反应-见正文]描述了不寻常的虹吸体代谢产物(-)-baconipyrone C(3)的不对称全合成。关键步骤包括用于制备羧酸17的锡(II)介导的醇醛偶联剂和导致醇8的两种不同的硼介导的醇醛添加剂加成反应。使用改良的Yamaguchi条件形成酯形成24,导致PMB脱保护为(-) -baconipyrone C.
Ilikonapyrone esters, likely defense allomones of the mollusk Onchidium verruculatum
作者:Chris M. Ireland、Joseph E. Biskupiak、Gilbert J. Hite、Michael Rapposch、Paul J. Scheuer、John R. Ruble