Enantioselective Allylation of Alkenyl Boronates Promotes a 1,2-Metalate Rearrangement with 1,3-Diastereocontrol
作者:Colton R. Davis、Irungu K. Luvaga、Joseph M. Ready
DOI:10.1021/jacs.1c01242
日期:2021.4.7
Alkenyl boronates add to Ir(π-allyl) intermediates with high enantioselectivity. A 1,2-metalate shift forms a second C–C bond and sets a 1,3-stereochemical relationship. The three-component coupling provides tertiary boronic esters that can undergo multiple additional functionalizations. An extension to trisubstituted olefins sets three contiguous stereocenters.
Cobalt-Catalyzed Diastereo- and Enantioselective Reductive Allyl Additions to Aldehydes with Allylic Alcohol Derivatives via Allyl Radical Intermediates
enantioenriched homoallylic alcohols with a remarkably broad scope of allyl groups that can be introduced. Mechanistic studies indicated that allyl radical intermediates were involved in this process. These new discoveries establish a new strategy for development of enantioselective transformations through capture of radicals by chiral Co complexes, pushing forward the frontier of Co complexes for enantioselective
Generation and Application of (Diborylmethyl)zinc(II) Species: Access to Enantioenriched <i>gem</i>
-Diborylalkanes by an Asymmetric Allylic Substitution
作者:Yeosan Lee、Jinyoung Park、Seung Hwan Cho
DOI:10.1002/anie.201805476
日期:2018.9.24
We report the successful generation of (diborylmethyl)zinc(II) species by transmetallation beteween isolable (diborylmethyl)lithium and zinc(II) halide (X=Br, Cl) and their application in the synthesis of enantioenriched gem‐diborylalkanes bearing a stereogenic center at the β‐position of the diboryl groups by an asymmetric allylic substitution reaction. The reaction has a broad substrate scope, and
A Modular Approach to Aryl-<i>C</i>-ribonucleosides via the Allylic Substitution and Ring-Closing Metathesis Sequence. A Stereocontrolled Synthesis of All Four α-/β- and <scp>d</scp>-/<scp>l</scp>-<i>C</i>-Nucleoside Stereoisomers
作者:Jan Štambaský、Vojtěch Kapras、Martin Štefko、Ondřej Kysilka、Michal Hocek、Andrei V. Malkov、Pavel Kočovský
DOI:10.1021/jo201110z
日期:2011.10.7
generated from (S)-5a, with the enantiopure allylic carbonates (R)-9a,b has been developed as the key step in a new approach to C-nucleoside analogues. The anomeric center was thus constructed via a stereocontrolled formation of the C–O rather than C–C bond with retention of configuration. The resulting bisallyl ethers 15a,b (≥90% de and >99% ee) were converted into C-ribosides 29a,b via the Ru-catalyzed
(S)-5a生成的对映纯单保护的铜(I)对映体的铱(I)催化与对映纯烯丙基碳酸酯(R)-9a,b的烯丙基化反应已成为开发C的新方法的关键步骤-核苷类似物。因此,异头物中心是通过立体控制形成的C–O而非C–C键并保留构型而构建的。将所得的双烯丙基醚15a,b(de≥90%,ee≥99 %)转化为C-核苷29a,b通过Ru催化的闭环复分解,然后由OsO 4或RuO 4催化的非对映选择性二羟基化和脱保护。起始片段5a和9a,b的绝对构型的变化允许所有四个α/β- d / l-组合的立体控制合成。
Auto‐Tandem Cooperative Catalysis Using Phosphine/Palladium: Reaction of Morita–Baylis–Hillman Carbonates and Allylic Alcohols
here is an unprecedented auto‐tandem cooperative catalysis (ATCC) for Morita–Baylis–Hillmancarbonates from isatins and allyliccarbonates using a simple Pd(PPh3)4 precursor. Dissociated phosphine generates phosphorusylides and the Pd leads to π‐allylpalladium complexes, and they undergo a γ‐regioselective allylic–allylic alkylation reaction. Importantly, a cascade intramolecular Heck‐type coupling proceeds