Traceless Stereoinduction in the One-Pot Assembly of All Three Rings of Hexahydrodibenzopyrans
作者:Keith A. Korthals、William D. Wulff
DOI:10.1021/ja077579m
日期:2008.3.1
stereochemical information from the chiral center at the propargylic ether in the alkyne to the planar center of chirality in the in situ generated arene chromium tricarbonyl complexed intermediate and finally, after base-induced elimination to generate an o-quinone methide chromium tricarbonyl complexed intermediate, a transfer of chiralityfrom the planar center of chirality in the o-quinone methide
employed to investigate asymmetric Nicholas reactions. We found that the use of a chiral N-enoyl derivative provided acceptable levels of selectivity for an intermolecular Nicholas reaction, however, we were unable to identify an auxiliary that could be utilized in an asymmetric conjugate addition and a tandem inter/intramolecular series of Nicholas reactions. The use of chiral pool non-racemic propargyl
Total Synthesis of Crenulatan Diterpenes: Strategy and stereocontrolled construction of a bicyclic keto-lactone building block
作者:Wei He、Emmanuel Pinard、Leo A. Paquette
DOI:10.1002/hlca.19950780210
日期:1995.3.22
implement acid-catalyzed isomerization to lactone 15, oxidation of which gave the pivotal aldehyde 16. Condensation of 16 with PhSeCH2Li led via21 to 22 (Scheme 3). Once the OH group was protected ( 22b), it proved possible to effect aldolization with crotonaldehyde ( 23). Exposure of 23 to acid gave the sub-target compound 25. Its subsequent oxidation and thermal activation resulted in sequential
合成双环酮内酯26的目的是开发一条可行的途径,以制取Crenulatan型海洋二萜。在将(S)-香茅醇(5)有效地转化为烯丙基化的醇9a(方案2)之后,有效地获得了αβ-不饱和内酯12,以准备立体控制的缀合物添加。最适合此任务的羟甲基当量为(i-PrO)Me 2 SiCH 2 MgCl,主要在CuI和Me 3 SiCl存在下给出13。OH基团脱保护后(14),事实证明,将酸催化异构化为内酯15很容易,氧化后可得到关键的醛16。16与PhSeCH 2 Li的缩合通过21引入到22(方案3)。一旦羟基被保护(22b),就证明可以用巴豆醛进行醛醇缩合(23)。将23暴露于酸下得到子目标化合物25。随后发生的氧化和热活化作用导致亚硒酸消除,并进行了克莱森重排(26)。26的结构特征要求在[3.3]渐近事件期间采用类似椅子的过渡状态。在澄清了这些问题之后,应该证明可以对轻型斜背肌进行高度维修和更高级的攻击了。
Soai, Kenso; Machida, Hideaki; Yokota, Noriko, Journal of the Chemical Society. Perkin transactions I, 1987, p. 1909 - 1914
作者:Soai, Kenso、Machida, Hideaki、Yokota, Noriko
DOI:——
日期:——
SOAI, KENSO;MACHIDA, HIDEAKI;YOKOTA, NORIKO, J. CHEM. SOC. PERKIN TRANS.,(1987) N 9, 1909-1914