Precatalyst‐Enabled Selectivity: Enantioselective NiH‐Catalyzed
anti
‐Hydrometalative Cyclization of Alkynones to
Endo
‐ and Heterocyclic Allylic Alcohols
摘要:
AbstractA highly enantioselective NiH‐catalyzed hydrocyclization of alkynones with unparalleled anti‐ and endocyclic selectivities is described. The choice of the precatalysts has significant influence in tuning the regio‐ and enantioselectivity. Using Ni(OTs)2/Phox as a precatalyst and (EtO)2MeSiH as a hydride source, an array of enantioenriched O‐, N‐, and S‐containing heterocyclic tertiary allylic alcohols are obtained in 24–81 % yields with 80:20–99:1 er. Mechanistic investigations and synthetic application are also carried out. This study represents an efficient access to a set of allylic alcohols that are unable to access by the state‐of‐the‐art coupling reactions.
Green Protocol for the O–H Insertion of α-Diazoketones with Alcohols and Water Using Ionic Liquid [Bmim]BF<sub>4</sub>
作者:J. S. Yadav、B. V. S. Reddy、M. Srinivas
DOI:10.1246/cl.2003.1060
日期:2003.11
α-Diazoketones undergo readily O–H insertion reactions with alcohols and water in hydrophilic [bmim]BF4 ionic liquid in the absence of any acid catalyst to furnish α-alkoxy and α-hydroxy ketones in excellent yields under neutral conditions. The recovered ionic liquid can be easily reused in four to five cycles with consistent in activity. The use of ionic liquid helps to avoid the use of acid catalysts as well as environmentally unfavorable volatile organic solvents.
Rhodium-Catalyzed Asymmetric Tandem Cyclization for Efficient and Rapid Access to Underexplored Heterocyclic Tertiary Allylic Alcohols Containing a Tetrasubstituted Olefin
作者:Yi Li、Ming-Hua Xu
DOI:10.1021/ol500993h
日期:2014.5.16
Rh-catalyzed asymmetric tandem cyclization of nitrogen- or oxygen-bridged 5-alkynones with arylboronic acids was achieved. The simple catalytic system involving a rhodium(I) complex with readily available chiral BINAP ligand promotes the reaction to proceed in a highly stereocontrolled manner. This protocol provides a very reliable and practical access to a variety of chiral heterocyclic tertiary allylic
Rhodium‐Catalyzed Asymmetric Cycloisomerization of 1,3‐Diketones with Keto‐Vinylidenecyclopropanes: Synthesis of Enantiomerically Enriched Cyclic
<i>β</i>
‐Amino Alcohols
作者:Chen Xu、Chao Ning、Song Yang、Yin Wei、Min Shi
DOI:10.1002/adsc.202001167
日期:2021.3.16
cyclic β‐amino alcohols via a rhodium‐catalyzed asymmetric cycloisomerization of 1,3‐diketones with keto‐vinylidenecyclopropanes. The reactions proceed through a Rh‐catalyzed transformation of keto‐vinylidenecyclopropanes via cleavage of the distal C−C bond of the three‐membered ring as a three‐carbon synthon, allowing the generation of a range of enantiomerically enriched cyclic β‐amino alcohols tethered
Visible-light induced metal-free intramolecular reductive cyclisations of ketones with alkynes and allenes
作者:Nana Tang、Raphael J. Zachmann、Hui Xie、Jun Zheng、Bernhard Breit
DOI:10.1039/d2cc06972e
日期:——
visible-light-induced, intramolecular, reductive cyclisation of ketones with an unsaturated hydrocarbon moiety was developed. In contrast to conventional protocols requiring resource precious or hazardous metal sources, this method enables facile access to ketyl radicals under metal-free and mild reaction conditions. By polarity-reversed, ketyl radical hydroalkoxylation of alkynes and allenes, a variety of
[3,3]-Sigmatropic rearrangements of propargyl alkynyl ethers. Synthesis of complex dienoates and unsaturated lactones
作者:Juan R. Sosa、Armen A. Tudjarian、Thomas G. Minehan
DOI:10.1039/d2ob02121h
日期:——
on low-temperature rearrangements of 1-alkynyl ethers, we describe herein the [3,3]-sigmatropic rearrangement of in situ formed propargyl alkynyl ethers to allenyl ketenes, which furnish complex tert-butyl-(2E,4Z)-dienoates 2 in good yields upon tert-butanol addition. Similarly, sigmatropic rearrangements of in situ formed propargyl lithioalkynyl ethers yield methyl-(2Z,4Z)-dienoates 4 upon methanol
在我们对 1-炔基醚的低温重排研究的扩展中,我们在本文中描述了原位形成的炔丙基炔基醚到联烯基乙烯酮的 [3,3]-σ 重排,其提供复杂的叔丁基-(2 E ,4 Z )-dienoates 2在加入叔丁醇后收率高。类似地,原位形成的炔丙基锂基炔基醚的 sigmatropic 重排在甲醇加成后产生甲基-(2 Z ,4 Z )-二烯酸酯4或在醛或酮加成丙二烯基炔诺酸酯中间体时产生不饱和内酯6 。