Total Synthesis of Aurofusarin: Studies on the Atropisomeric Stability of Bis-Naphthoquinones
AngewchemTotal Synthesis of Aurofusarin: Studies on the Atropisomeric Stability of Bis-NaphthoquinonesDr. Chao Qi, Dr. Wenyu Wang, Dr. Kyle D. Reichl, Dr. James McNeely and Prof. Dr. John A. Porco Jr.An efficient annulation involving pyrone addition to a quinone and Dieckmann condensation was developed for rapid assembly of a γ-naphthopyrone monomeric precursor to the bis-naphthoquinone natural product aurofusarin. Dimerization was achieved through PdII-catalyzed dehydrogenative coupling. (Source: Organometallic Current)
Source: Organometallic Current - January 31, 2018 Category: Chemistry Tags: Total synthesis Source Type: blogs
Review:Increasing Catalyst Efficiency in C −H Activation Catalysis
AngewchemIncreasing Catalyst Efficiency in C −H Activation CatalysisDr. Tobias Gensch, Dr. Michael J. James, Toryn Dalton and Prof. Dr. Frank GloriusC −H activation reactions with high catalyst turnover numbers are still very rare in the literature and 10 mol % is a common catalyst loading in this field. We offer a representative overview of efficient C−H activation catalysis to highlight this neglected aspect of catalysis development and inspire future effort towards more efficient C−H activation. Examples ranging from palladium catalysis, Cp*RhIII- and Cp*CoIII-catalysis, the C −H borylation and silylati...
Source: Organometallic Current - January 31, 2018 Category: Chemistry Tags: C-H Activation Reviews Source Type: blogs
Total Syntheses of Scaparvins B, C, and D Enabled by a Key C –H Functionalization
JacsTotal Syntheses of Scaparvins B, C, and D Enabled by a Key C –H Functionalization: The clerodane diterpene family possesses an impressive range of bioactivities and high synthetic challenge due to their unique amalgamation of rings, stereocenters, and oxygenation. Herein, we disclose the first total syntheses of three members, scaparvins B, C, and D, through a route fueled by several chemoselective and carefully orchestrated steps. (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: Total synthesis Source Type: blogs
Widely Applicable Hydrofluorination of Alkenes via Bifunctional Activation of Hydrogen Fluoride
JacsWidely Applicable Hydrofluorination of Alkenes via Bifunctional Activation of Hydrogen Fluoride: Expanding the use of fluorine in pharmaceuticals, agrochemicals and materials requires a widely applicable and more efficient protocol for the preparation of fluorinated compounds. We have developed a new generation nucleophilic fluorination reagent, KHSO4-13HF, HF 68 wt/wt %, that is not only easily handled and inexpensive but also capable of hydrofluorinating diverse, highly functionalized alkenes, including natural products. (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: Fluorination Source Type: blogs
Three ‐Component Enantioselective Cyclization Reaction Catalyzed by an Unnatural Amino Acid Derivative
AngewchemThree ‐Component Enantioselective Cyclization Reaction Catalyzed by an Unnatural Amino Acid Derivative: A new diastereo ‐ and enantioselective three‐component cyclization reaction is described. The reaction takes place between a ketone, a carboxylic acid, and a nitroalkene to yield a bicyclic octahydro‐2H‐indol‐2‐one... (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: Enantioselective Multicomponent Rxn organocatalysis Source Type: blogs
A Six ‐Oxidase Cascade for Tandem C−H Bond Activation Revealed by Reconstitution of Bicyclomycin Biosynthesis
AngewchemA Six ‐Oxidase Cascade for Tandem C−H Bond Activation Revealed by Reconstitution of Bicyclomycin Biosynthesis: As a commercial antibiotic, bicyclomycin (BCM) is currently the only known natural product targeting the transcription termination factor rho. It belongs to a family of highly functionalized diketopiperazine... (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: Biosynthesis C-H Activation Source Type: blogs
Asymmetric Synthesis of 2H ‐Azirines with a Tetrasubstituted Stereocenter by Enantioselective Ring Contraction of Isoxazoles
AngewchemAsymmetric Synthesis of 2H ‐Azirines with a Tetrasubstituted Stereocenter by Enantioselective Ring Contraction of Isoxazoles: Highly strained 2H ‐azirines with a tetrasubstituted stereocenter were synthesized by the enantioselective isomerization of isoxazoles with a chiral diene–rhodium catalyst system. The effect of ligands... (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: Asymmetric Rh Catalyzed Ring contraction Source Type: blogs
Distal Weak Coordination of Acetamides in Ruthenium(II) ‐Catalyzed C−H Activation Processes
AngewchemDistal Weak Coordination of Acetamides in Ruthenium(II) ‐Catalyzed C−H Activation Processes: C −H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C−H functionalization offers ample scope—including twofold oxidative C−H... (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: C-H Activation Ru catalyzed Source Type: blogs
Enantioselective Synthesis of N,S ‐Acetals by an Oxidative Pummerer‐Type Transformation using Phase‐Transfer Catalysis
AngewchemEnantioselective Synthesis of N,S ‐Acetals by an Oxidative Pummerer‐Type Transformation using Phase‐Transfer Catalysis: Reported is the first enantioselective oxidative Pummerer ‐type transformation using phase‐transfer catalysis to deliver enantioenriched sulfur‐bearing heterocycles. This reaction includes the direct oxidation... (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: Enantioselective Phase Transfer Catalysis Source Type: blogs
Macrolide Synthesis trough Intramolecular Oxidative Cross ‐Coupling of Alkenes
AngewchemMacrolide Synthesis trough Intramolecular Oxidative Cross ‐Coupling of Alkenes: A RhIII ‐catalyzed intramolecular oxidative cross‐coupling between double bonds for the synthesis of macrolides is described. Under the optimized reaction conditions, macrocycles containing a diene moiety... (Source: Organometallic Current)
Source: Organometallic Current - December 13, 2017 Category: Chemistry Tags: C-H Activation Macrocyclization Rh Catalyzed Source Type: blogs
Palladium-Catalyzed Dearomative syn-1,4-Carboamination
JacsPalladium-Catalyzed Dearomative syn-1,4-Carboamination: A dearomative 1,4-carboamination of arenes has been achieved using arenophile cycloaddition and subsequent palladium-catalyzed substitution with nonstabilized lithium enolates. This protocol delivers products with exclusivesyn-1,4-selectivity and can be also conducted in an asymmetric fashion. (Source: Organometallic Current)
Source: Organometallic Current - December 11, 2017 Category: Chemistry Tags: Carboamination Dearomatization Pd Catalyzed Source Type: blogs
Catalyst-Controlled Diastereoselective Synthesis of Cyclic Amines via C –H Functionalization
This report describes a catalyst-controlled regio- and diastereoselective synthesis ofN-unprotected pyrrolidines via dirhodium catalyzed intramolecular nitrene insertion into sp3 C –H bonds. The reaction proceeds at rt without external oxidants, nitrene stabilizing groups, or directing functionality. (Source: Organometallic Current)
Source: Organometallic Current - December 11, 2017 Category: Chemistry Tags: C-H Functionalization Diastereoselective Rh Catalyzed Source Type: blogs
Ni –Al Bimetallic Catalyzed Enantioselective Cycloaddition of Cyclopropyl Carboxamide with Alkyne
JacsNi –Al Bimetallic Catalyzed Enantioselective Cycloaddition of Cyclopropyl Carboxamide with Alkyne: A Ni –Al bimetallic catalyzed enantioselective cycloaddition reaction of cyclopropyl carboxamides with alkynes has been developed. A series of cyclopentenyl carboxamides were obtained in up to 99% yield and 94% ee. The bifunctional-ligand-enabled bimetallic catalysis proved to be an efficient strat egy for the C–C bond cleavage of unreactive cyclopropanes. (Source: Organometallic Current)
Source: Organometallic Current - December 11, 2017 Category: Chemistry Tags: Cycloaddition Enantioselective Ni Catalyzed Source Type: blogs
Zn-ProPhenol Catalyzed Enantio- and Diastereoselective Direct Vinylogous Mannich Reactions between α,β- and β,γ-Butenolides and Aldimines
We report a Zn-ProPhenol catalyzed reaction between butenolides and imines to obtain tetrasubstituted vinylogous Mannich products in good yield and diastereoselectivity with excellent enantioselectivity (97 to>99.5%ee). Notably, both α,β- and β,γ-butenolides can be utilized as nucleophiles in this transformation. (Source: Organometallic Current)
Source: Organometallic Current - December 11, 2017 Category: Chemistry Tags: Enantioselective Mannich Reaction Zn Catalyzed Source Type: blogs
Highly Selective Manganese(I)/Lewis Acid Cocatalyzed Direct C −H Propargylation Using Bromoallenes
AngewchemHighly Selective Manganese(I)/Lewis Acid Cocatalyzed Direct C −H Propargylation Using Bromoallenes: A manganese(I)/Lewis acid cocatalyzed direct C −H propargylation with high selectivity has been developed. BPh3 was discovered to not only promote the reactivity, but also enhance the selectivity. Secondary,... (Source: Organometallic Current)
Source: Organometallic Current - December 11, 2017 Category: Chemistry Tags: Mn catalyzed Propargylation Source Type: blogs
