Generation and Reaction of Monocarbonyliodonium Ylides: Ester Exchange of (<i>Z</i>)-(β-Acetoxyvinyl)iodonium Salts with Lithium Ethoxide and Synthesis of α,β-Epoxy Ketones
generation of monocarbonyliodonium ylides and their alkylidene-transfer reactions to aldehydes yielding α,β-epoxy ketones. Exposure of (Z)-(2-acetoxy-1-decenyl)iodonium bromide, prepared stereoselectively by sodium acetate-catalyzed Michael addition of acetic acid to (1-decynyl)(phenyl)iodonium salt, to EtOLi in THF at −78 °C results in ester exchange to generate the monocarbonyliodonium ylide with the liberation
这里首次报道了单羰基碘鎓叶立德的产生及其亚烷基转移反应到醛,产生 α,β-环氧酮。(Z)-(2-乙酰氧基-1-癸烯基)溴化碘,通过乙酸钠催化迈克尔加成乙酸与(1-癸炔基)(苯基)碘盐的立体选择性制备,暴露于-78°THF中的EtOLi C 导致酯交换以生成单羰基碘鎓叶立德,同时释放乙酸乙酯。1H NMR 测量表明,叶立德在 THF-d8 中可稳定至 -30 °C,但在 -20 °C 时逐渐分解为 1-bromo-2-decanone。单羰基碘鎓叶立德作为羰基化合物的亚烷基转移剂,在-30°C 下与 THF-DMSO 中的醛反应得到 α,β-环氧酮,主要产物为 E-异构体。与α,β-不饱和醛,观察到羰基的选择性 1,2-加成。该叶立德的亚烷基转移反应对一系列环取代的苯甲醛的相对速率...
A Method for the Late-Stage Formation of Ketones, Acyloins, and Aldols from Alkenylstannanes: Application to the Total Synthesis of Paecilonic Acid A
作者:Heiko Sommer、James Y. Hamilton、Alois Fürstner
DOI:10.1002/anie.201701391
日期:2017.5.22
Treatment of alkenylstannanes with Cu(OAc)2 /Et3 N affords the corresponding enol esters or ketones under conditions that proved compatible with many common functionalities; these include groups that would neither survive under the standard Tamao-Fleming conditions for the oxidation of Csp2 -SiR3 bonds nor under the conditions commonly used to oxidize C-B bonds. Chiral centers adjacent to the unveiled
在证明与许多常见功能兼容的条件下,用Cu(OAc)2 / Et 3 N处理烯基锡烷可得到相应的烯醇酯或酮。这些包括在标准的Tamao-Fleming条件下不能氧化Csp2-SiR 3键或在通常用于氧化CB键的条件下都无法生存的基团。即使底物带有未保护的-OH基团作为内部质子源,与新发现的羰基相邻的手性中心也不会外消旋,竞争性去锡烷基化反应是微不足道的。因此,该方法非常适合于制备酰基里昂和醛醇衍生物。这些促成的优点通过对双环脂质pa酸A的简洁方法加以说明。
A New Route for Generation of α-λ<sup>3</sup>-Iodanyl Ketones via Ester Exchange of (<i>Z</i>)-(β-Acetoxyvinyl)-λ<sup>3</sup>-iodanes: Their Nucleophilic Substitutions with Halides and Sulfur and Phosphorus Nucleophiles
作者:Masahito Ochiai、Junichi Nishitani、Yoshio Nishi
DOI:10.1021/jo0107711
日期:2002.6.1
An efficient method for generation of alpha-lambda3-iodanyl ketones from (Z)-(2-acetoxyvinyl)(phenyl)-lambda3-iodanes was developed. The method involves ester exchange of (Z)-2-acetoxyvinyl-lambda3-iodanes with methanol in the presence of triethylamine. alpha-lambda3-Iodanyl ketones react with a variety of nucleophiles such as halides, thiols, phosphines, phosphinic acids, and phosphates, under the