Nine-Membered Benzofuran-Fused Heterocycles: Enantioselective Synthesis by Pd-Catalysis and Rearrangement via Transannular Bond Formation
JacsNine-Membered Benzofuran-Fused Heterocycles: Enantioselective Synthesis by Pd-Catalysis and Rearrangement via Transannular Bond Formation: The first enantioselective formal [5+4] cycloaddition is realized under palladium catalysis to deliver benzofuran-fused nine-membered rings. These medium-sized heterocycles and derivatives undergo unique rearrangements induced by transannular bond formation, resulting in the production of two classes of densely substituted polycyclic heterocycles in excellent efficiency and stereoselectivity. (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Pd Catalyzed Source Type: blogs
Cobalt-Catalyzed Asymmetric Sequential Hydroboration/Hydrogenation of Internal Alkynes
JacsCobalt-Catalyzed Asymmetric Sequential Hydroboration/Hydrogenation of Internal Alkynes: A highly regio- and enantioselective cobalt-catalyzed hydroboration/hydrogenation of internal alkynes with HBpin and a hydrogen balloon in one pot was developed. A new type of chiral imidazoline iminopyridine (IIP) ligand was introduced for the first time in this novel and efficient strategy. This protocol used relatively simple and available starting materials with good functional group tolerance to construct more valuable chiral secondary organoboronates. (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Co catalyzed Hydroboration Hydrogenation Source Type: blogs
Stereospecific Allylic Functionalization: The Reactions of Allylboronate Complexes with Electrophiles
JacsStereospecific Allylic Functionalization: The Reactions of Allylboronate Complexes with Electrophiles: Allylboronic esters react readily with carbonyls and imines ( π-electrophiles), but are unreactive toward a range of other electrophiles. By addition of an aryllithium, the corresponding allylboronate complexes display enhanced nucleophilicity, enabling addition to a range of electrophiles (tropylium, benzodithiolylium, activated pyridines, Eschenmoser’ s salt, Togni’s reagent, Selectfluor, diisopropyl azodicarboxylate (DIAD), MeSX) in high regio- and stereocontrol. This protocol provides access to key new functi...
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Allylic Source Type: blogs
A Mild Hydroaminoalkylation of Conjugated Dienes Using a Unified Cobalt and Photoredox Catalytic System
JacsA Mild Hydroaminoalkylation of Conjugated Dienes Using a Unified Cobalt and Photoredox Catalytic System: Metallo-photoredox catalysis has redefined the available bond disconnections in the synthetic arsenal. By harnessing the one-electron chemistry of photoredox catalysis in tandem with low-valent cobalt catalysts, new methods by which functionalities may be stitched together become available. Herein we describe the coupling of photoredox-generated α-amino radical species with conjugated dienes using a unified cobalt and iridium catalytic system in order to access a variety of useful homoallylic amines from simple com...
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Co catalyzed Photoredox Catalysis Source Type: blogs
Iron-Catalyzed Regioselective Anti-Markovnikov Addition of C –H Bonds in Aromatic Ketones to Alkenes
We report here on a C –H alkylation reaction, in which the coupling of aromatic ketones with alkenes proceeds in the presence of only a simple Fe(PMe3)4 catalyst. The anti-Markovnikov addition of ortho C –H bonds in various ketones occurs with excellent regioselectivity under relatively mild reaction conditions. (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Anti Markovnikov addition Fe catalyzed Source Type: blogs
Catalytic Asymmetric Synthesis of Quaternary Barbituric Acids
In this study 2-alkylthio-4,6-dioxopirimidines are designed as key 1,3-diamide surrogates that perfor m exceedingly in amine-squaramide catalyzed C–C bond forming reactions with vinyl ketones or Morita–Baylis–Hillmann-type allyl bromides as electrophiles. (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Asymmetric Source Type: blogs
Through-Space Activation Can Override Substituent Effects in Electrophilic Aromatic Substitution
In this report, we present unique examples of electron-deficient arenes instead undergoing preferential substitution in intramolecular competition with m ore electron-rich rings. (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Electrophilic aromatic substitution Source Type: blogs
Total Synthesis of Longeracinphyllin A
JacsTotal Synthesis of Longeracinphyllin A: The first and asymmetric total synthesis of longeracinphyllin A, a hexacyclicDaphniphyllum alkaloid, has been accomplished. A tetracyclic intermediate was prepared through silver-catalyzed alkyne cyclization and Luche radical cyclization. A phosphine-promoted [3 + 2] cycloaddition reaction was exploited to construct the sterically congested E ring bearing vicinal tertiary and quaternary centers. (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Total synthesis Source Type: blogs
Synthesis of Arylamines via Aminium Radicals
AngewchemSynthesis of Arylamines via Aminium Radicals: Arylamines constitute the core structure of many therapeutic agents, agrochemicals, and organic materials. The development of methods for the efficient and selective construction of these structural motifs... (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Radical Reactions Source Type: blogs
Catalytic Reduction of Alkyl and Aryl Bromides Using Propan ‐2‐ol
AngewchemCatalytic Reduction of Alkyl and Aryl Bromides Using Propan ‐2‐ol: Milstein's complex, (PNN)RuHCl(CO), catalyzes the efficient reduction of aryl and alkyl halides under relatively mild conditions by using propan ‐2‐ol and a base. Sterically hindered tertiary and neopentyl... (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Reduction Ru catalyzed Source Type: blogs
Ruthenium ‐Catalyzed para‐Selective C−H Alkylation of Aniline Derivatives
AngewchemRuthenium ‐Catalyzed para‐Selective C−H Alkylation of Aniline Derivatives: The para ‐selective C−H alkylation of aniline derivatives furnished with a pyrimidine auxiliary is herein reported. This reaction is proposed to take place via an N−H‐activated cyclometalate formed in situ.... (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: C-H alkylation para selective Ru catalyzed Source Type: blogs
Diastereoselective Construction of Densely Functionalized 1 ‐Halocyclopentenes Using an Alkynyl Halo‐Prins/Halo‐Nazarov Cyclization Strategy
AngewchemDiastereoselective Construction of Densely Functionalized 1 ‐Halocyclopentenes Using an Alkynyl Halo‐Prins/Halo‐Nazarov Cyclization Strategy: A diastereoselective two ‐step strategy for the synthesis of densely functionalized 1‐halocyclopentenes with several chiral centers has been developed. In the first step, a multicomponent alkynyl halo‐Prins... (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Diastereoselective Nazarov Cyclization Prins Cyclization Source Type: blogs
Copper ‐Catalyzed Synthesis of γ‐Amino Acids Featuring Quaternary Stereocenters
: The first general asymmetric synthesis of γ,γ‐disubstituted γ‐amino acids by copper‐catalyzed ring opening of nonstrained lactones with amines is reported. This approach features ample scope, operational... (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Aminoacids Cu catalyzed Source Type: blogs
Synergistic Manganese(I) C −H Activation Catalysis in Continuous Flow: Chemoselective Hydroarylation
AngewchemSynergistic Manganese(I) C −H Activation Catalysis in Continuous Flow: Chemoselective Hydroarylation: Chemoselective hydroarylations were accomplished by a novel synergistic Br ønsted acid/manganese(I)‐catalyzed C−H activation manifold. Thus, alkynes bearing O‐leaving groups could, for the first time, be... (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: C-H Activation Continuous Flow Synthesis Mn catalyzed Source Type: blogs
Iridium ‐Catalyzed Asymmetric Allylic Dearomatization by a Desymmetrization Strategy
AngewchemIridium ‐Catalyzed Asymmetric Allylic Dearomatization by a Desymmetrization Strategy: A desymmetrization strategy was developed involving iridium ‐catalyzed allylic dearomatization of indoles. The six‐membered‐ring spiroindolenines contain three contiguous stereogenic centers, including... (Source: Organometallic Current)
Source: Organometallic Current - October 25, 2017 Category: Chemistry Tags: Allylic Dearomatization Ir catalyzed Source Type: blogs
