Asymmetric, anti-Selective Scandium-Catalyzed Sakurai Additions to Glyoxyamide. Applications to the Syntheses of N-Boc d-Alloisoleucine and d-Isoleucine
摘要:
An enantio- and diastereoselective Sakurai-Hosomi reaction, catalyzed by chiral scandium pyridyl-bis(oxazoline) (pybox) complexes, has been developed. Both alkyl- and aryl-substituted allylsilanes are effective coupling partners with N-phenylglyoxamide. Applications of this reaction to the asymmetric syntheses of N-BOC D-alloisoleucine and D-isoleucine are described.
Orthogonally Protected 1,2-Diols from Electron-Rich Alkenes Using Metal-Free Olefin <i>syn</i>-Dihydroxylation
作者:Ignacio Colomer、Rosimeire Coura Barcelos、Kirsten E. Christensen、Timothy J. Donohoe
DOI:10.1021/acs.orglett.6b02959
日期:2016.11.18
A new method for the stereoselective metal-free syn-dihydroxylation of electron-richolefins is reported, involving reaction with TEMPO/IBX in trifluoroethanol (TFE) or hexafluoroisopropanol (HFIP) and the addition of a suitable nucleophile. Orthogonally protected syn 1,2-diols were obtained with high levels of diastereocontrol, and these products were selectively deprotected and selectively functionalized
Transformation of <i>N</i>,<i>N</i>-Dimethylaniline <i>N</i>-Oxides into Diverse Tetrahydroquinoline Scaffolds via Formal Povarov Reactions
作者:Timothy S. Bush、Glenn P. A. Yap、William J. Chain
DOI:10.1021/acs.orglett.8b02318
日期:2018.9.7
A one-pot protocol for the assembly of diversely functionalized tetrahydro-, hexahydrofuro-, hexahydropyrano-, and tetrahydrobenzofuroquinolines from N,N-dimethylaniline N-oxides and various electron-rich olefins in a tandem Polonovski–Povarov sequence is reported. Following activation of the N–O bond with Boc2O, an exocyclic iminium ion is unveiled upon exposure to tin(IV) chloride. A formal inverse-electron-demand
Rational Design of a Second Generation Catalyst for Preparation of Allylsilanes Using the Silyl-Heck Reaction
作者:Jesse R. McAtee、Glenn P. A. Yap、Donald A. Watson
DOI:10.1021/ja505446y
日期:2014.7.16
second-generation ligand, bis(3,5-di-tert-butylphenyl)(tert-butyl)phosphine, for the preparation of allylsilanes using the palladium-catalyzed silyl-Heck reaction. This new ligand provides nearly complete suppression of starting material alkene isomerization that was observed with our first-generation catalyst, providing vastly improved yields of allylsilanes from simple alkene starting materials.
使用合理的配体设计,我们开发了第二代配体,双(3,5-二叔丁基苯基)(叔丁基)膦,用于使用钯催化的甲硅烷基-Heck 反应制备烯丙基硅烷。这种新的配体几乎完全抑制了我们的第一代催化剂所观察到的原料烯烃异构化,大大提高了从简单烯烃原料中获得的烯丙基硅烷的产率。描述了量化新配体的电子和空间特性的研究。最后,我们报告了使用类似配体氧化加成 Me3SiI 产生的钯络合物的 X 射线晶体结构,该结构提供了对催化系统性质的重要洞察。
Preparation of Allyl and Vinyl Silanes by the Palladium-Catalyzed Silylation of Terminal Olefins: A Silyl-Heck Reaction
作者:Jesse R. McAtee、Sara E. S. Martin、Derek T. Ahneman、Keywan A. Johnson、Donald A. Watson
DOI:10.1002/anie.201200060
日期:2012.4.10
high‐yielding protocol for the palladium‐catalyzed silylation of terminal alkenes is reported. This method allows facileconversion of styrenes to E‐β‐silyl styrenes by using iodotrimethylsilane (TMSI) or chlorotrimethylsilane/lithium iodide (see scheme). Terminal allyl silanes with good E/Z ratios are also readily accessed from α‐olefins.
A Bench-Stable, Single-Component Precatalyst for Silyl–Heck Reactions
作者:Sarah B. Krause、Jesse R. McAtee、Glenn P. A. Yap、Donald A. Watson
DOI:10.1021/acs.orglett.7b02807
日期:2017.10.20
reaction aimed at identifying active palladium complexes have revealed a new species that is formed in situ. This complex has been identified as the palladium iodide dimer, [(JessePhos)PdI2]2, which has been found to be a competent single-component precatalyst for the silyl-Heck reaction. This complex is easily prepared and is temperature, moisture, and airstable. Additionally, this precatalyst provides