Both enantiomers of sabina ketone were efficiently prepared via an easy synthesis of 1-diazo-5-methylene-6-methylheptan-2-one, starting from succinic anhydride, followed by its highly enantioselective cyclization catalyzed by chiral dirhodium(II) compounds having ortho-metalated phosphines as ligands. (C) 2003 Published by Elsevier Ltd.
Diastereoselective Intramolecular Cyanoamidation with Alkenes
作者:Ashley M. Dreis、Sadie C. Otte、Matthew S. Eastwood、Elizabeth R. Alonzi、Jason T. Brethorst、Christopher J. Douglas
DOI:10.1002/ejoc.201601283
日期:2017.1.3
Reported herein is a diastereoselective intramolecularalkene cyanoamidation, wherein high d.r. values are imparted by chiral directing groups. Lactams with an α-all-carbon quaternary stereocenter are readily synthesized, which may enable access to structures frequently found in biologically active molecules and natural products.
本文报道了非对映选择性分子内烯烃氰基酰胺化,其中手性导向基团赋予高 dr 值。具有α-全碳四元立体中心的内酰胺很容易合成,这可能使我们能够获得在生物活性分子和天然产物中常见的结构。
Directed γ-C(sp<sup>3</sup>)–H Alkylation of Carboxylic Acid Derivatives through Visible Light Photoredox Catalysis
作者:Dian-Feng Chen、John C. K. Chu、Tomislav Rovis
DOI:10.1021/jacs.7b09306
日期:2017.10.25
Visible light photoredox catalysis enables direct γ- C(sp3)-H alkylation of saturated aliphatic carbonyl compounds. Electron-deficient alkenes are used as the coupling partners in this reaction. Distinguished site selectivity is controlled by the predominant 1,5-hydrogen atom transfer of an amidyl radical generated in situ.
The apple never falls far from the tree: S‐alkylthiocarbamate 1 (see scheme, NBP=N‐bromophthalimide) was prepared in high yield through a synthetic sequence involving a Newman–Kwart rearrangement of the corresponding O‐alkylthiocarbamates. Compound 1 was used to catalyze bromolactonization, thus providing enantioenriched δ‐lactones in excellent yield and enantioselectivity.
among stereocontrolled iodocyclizations mostly substrate-controlled versions using a chiral auxiliary have been successfully investigated. This work reports on stereoselective reagent-controlled iodolactonizations applying a new method using a combination of ICl and a primary amine leading to the highest selectivities known so far.
Nitrene‐Mediated Enantioselective Intramolecular Olefin Oxyamination to Access Chiral γ‐Aminomethyl‐γ‐Lactones
作者:Xin Nie、Clayton W. Ritter、Marcel Hemming、Sergei I. Ivlev、Xiulan Xie、Shuming Chen、Eric Meggers
DOI:10.1002/anie.202314398
日期:2023.12.18
Nitrene-mediated asymmetric intramolecularolefin difunctionalization is introduced, in which the nitrene intermediate adds in an unprecedented exocyclic fashion and the nucleophile in an endocyclic fashion. This atom-economic strategy affords chiral γ-aminomethyl-γ-lactones in high yields and excellent enantioselectivities and provides access to versatile chiral building blocks.