Catalytic C–F bond activation of geminal difluorocyclopropanes by nickel(i) complexes via a radical mechanism

2016 ◽  
Vol 52 (1) ◽  
pp. 202-205 ◽  
Author(s):  
Jan Wenz ◽  
Christoph A. Rettenmeier ◽  
Hubert Wadepohl ◽  
Lutz H. Gade
Keyword(s):  
Good Yield ◽  
Ring Opening ◽  
Bond Activation ◽  
Radical Mechanism ◽  
Pincer Ligands

Nickel(ii) fluorido complexes bearing NNN-pincer ligands were found to be catalysts in the hydrodefluorination of geminal difluorocyclopropanes which undergo ring-opening to form the corresponding monofluoroalkenes in good yield and high Z-selectivities.

Recent Advances in Transition Metal Catalyzed C-H Functionalization Reactions Involving Aza/Oxabicyclic Alkenes

Synthesis ◽  
2021 ◽  
Author(s):  
Masilamani Jeganmohan ◽  
Pinki Sihag
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Ring Opening ◽  
Bond Activation ◽  
Considerable Progress ◽  
Double Bonds ◽  
Facial Selectivity ◽  
Ring Opening Reactions ◽  
Metal Catalyzed

Bicyclic alkenes, including Oxa- and azabicyclic alkenes can be readily activated by using transition-metal complexes with facial selectivity, because of the intrinsic angle strain on carbon-carbon double bonds of these unsymmetrical bicyclic systems. During last decades considerable progress has been done in the area of ring-opening of bicyclic strained ring by employing the concept of C-H activation. This Review comprehensively compiles the various C-H bond activation assisted reactions of oxa- and azabicyclic alkenes, viz., ring-opening reactions, hydroarylation as well as annulation reactions.

scholarly journals Rhodium(III)-Catalyzed Three-Component 1,2-Diamination of Unactivated Terminal Alkenes

Synthesis ◽  
2019 ◽  
Vol 52 (08) ◽  
pp. 1247-1252 ◽  
Author(s):  
Sumin Lee ◽  
Young Jin Jang ◽  
Erik J. T. Phipps ◽  
Honghui Lei ◽  
Tomislav Rovis
Keyword(s):  
Good Yield ◽  
Ring Opening ◽  
Secondary Amines ◽  
One Pot ◽  
Rapid Access ◽  
Primary And Secondary Amines ◽  
Terminal Alkenes ◽  
Broad Array ◽  
Vicinal Diamines

We report a three-component diamination of simple unactivated alkenes using an electrophilic nitrene source and amine nucleo­philes. The reaction provides rapid access to 1,2-vicinal diamines from terminal alkenes through a one-pot protocol. The transformation proceeds smoothly with excellent tolerance for a broad array of primary and secondary amines, affording the desired products in good yield and regioselectivity. The mechanism is proposed to proceed through a Rh(III)-catalyzed aziridination of alkenes with subsequent ring opening by primary or secondary amines.

Arene chromium complexes with functionalized anellated rings. Selective formation of highly substituted polycycles

2002 ◽  
Vol 74 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Holger Butenschön
Keyword(s):  
Good Yield ◽  
Ring Opening ◽  
Ring Expansion ◽  
Chromium Complexes ◽  
Ketone Group ◽  
Aldol Additions ◽  
Cope Rearrangements ◽  
Hydrolysis Of ◽  
Selective Formation ◽  
Tricarbonylchromium Complexes

Tricarbonylchromium complexes of benzocyclobutenone, benzocyclobutenedione, and 1,3-indandione are readily prepared by hydrolysis of the complexes of the corresponding acetals. Reduction of the benzocyclobutenone complex gives rise to an oxy-anion-driven ring opening to the corresponding ortho-quinodimethane intermediate, which can be trapped with dienophiles. Addition of 1-ethoxy-1-lithioethene allows a stereoselective ring expansion followed by an anionic ketol rearrangement with complete diastereoselectivity. Addition of 1-lithio-1-methoxyallene gives rise to a rare anionic 1-vinylcyclobutenol-cyclohexadienol rearrangement. Diaddition of alkenylmetal reagents at both keto groups in benzoyclobutenedione complexes causes dianionic oxy-Cope rearrangements to occur at ­78 °C, which are followed by diastereoselective intramolecular aldol additions. In some cases, a completely regioselective mono hydrolysis of di(enolates) was observed. Dianionic oxy-Cope rearrangements can also be realized with unstrained benzil derivatives giving 1,6-hexanediones and the corresponding aldol adducts. The 1,2,3-indantrione complex is obtained by oxidation of the 1,3-indandione complex with dimethyldioxirane in good yield and reacts with its central ketone group in hetero Diels­Alder cycloadditions.

Application of Rh(I)-Catalyzed C−H Bond Activation to the Ring Opening of 2-Cycloalkenones in the Presence of Amines

2002 ◽  
Vol 4 (9) ◽  
pp. 1595-1597 ◽  
Author(s):  
Chul-Ho Jun ◽  
Choong Woon Moon ◽  
Sung-Gon Lim ◽  
Hyuk Lee
Keyword(s):  
Ring Opening ◽  
Bond Activation

Model Compounds Related to Saquayamycin. Attempts to Oxygenate the A/B Ring Junction

2002 ◽  
Vol 55 (5) ◽  
pp. 343 ◽  
Author(s):  
M. A. Apponyi ◽  
J. H. Bowie ◽  
B. W. Skelton ◽  
A. H. White
Keyword(s):  
Double Bond ◽  
Maleic Anhydride ◽  
Good Yield ◽  
Ring Opening ◽  
Diels Alder ◽  
Aromatic System ◽  
Model Compounds ◽  
Similar Treatment ◽  
Ring Junction

The aim of this project was to attempt to find a method for introducing the cis-dihydroxyl substitution at the A/B-ring junction of model compounds related to the saquayamycins. The Diels-Alder reactions of maleic anhydride and bromomaleic anhydride with 5,5-dimethyl-3-vinylcyclohexa-1,2-dienyl acetate gave the two required endo-adducts in good yield, namely (octahydrobenzo[e]isobenzofuran-9-yl acetate (6) and (octahydrobenzo[e]isobenzofuran-9-yl acetate (9). Each of these was converted into the B-ring mono-epoxide, namely (H-benzo[e]oxireno-2,3-furan-1-yl acetate (7) and a mixture of two racemic diastereoisomers of 9a-bromo-3,3-dimethyl-7,9-dioxoperhydrobenzo[e]oxi- reno[2,3-f]isobenzofuran-1-yl acetate (12), respectively. It was then hoped to deprotonate both (7) and (12) at the 9a position in order to effect migration of the 8,9 double bond to the 9,9a position. Reaction of (7) with a mild base (pyridine) did not effect any reaction. Similar treatment of (12) did remove the 9a proton, but it also effected ring opening of the epoxide, followed by dehydration and dehydrobromination to give an excellent (but unwanted) yield of the aromatized system (±)-7,7-dimethyl-1,3-dioxo-1,3,5,7-tetrahydrobenzo (e]isobenzofuran-9-yl acetate. Dehydrobromination of (9), and deprotonation of the 9a position, similarly formed the aromatic system (e]isobenzofuran-9-yl acetate (11) in good yield.

CH Bond Activation of Unsaturated Hydrocarbons by a Niobium Methyl Cyclopropyl Precursor. Cyclopropyl Ring Opening and Alkyne Coupling Reaction

2016 ◽  
Vol 36 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Pascal Oulié ◽  
Chiara Dinoi ◽  
Chen Li ◽  
Alix Sournia-Saquet ◽  
Kane Jacob ◽  
...  
Keyword(s):  
Ring Opening ◽  
Bond Activation ◽  
Coupling Reaction ◽  
Unsaturated Hydrocarbons ◽  
Ch Bond Activation ◽  
Alkyne Coupling

scholarly journals An Efficient and Mild Method for the Synthesis and Hydrazinolysis ofN-Glyoxylamino Acid Esters

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ayman El-Faham ◽  
Zainab Al Marhoon ◽  
Ahmed Abdel-Megeed ◽  
Mohamed Siddiqui
Keyword(s):  
Hydrazine Hydrate ◽  
Good Yield ◽  
Acid Ester ◽  
Ring Opening ◽  
Acid Hydrazide ◽  
Type Reaction ◽  
H Nmr ◽  
Elemental Microanalysis ◽  
Acid Esters ◽  
C Nmr

N-Glyoxylamino acid ester derivatives were synthesized via the ring opening ofN-acetylisatin using moderate conditions. During the hydrazinolysis ofN-glyoxylamino acid ester derivatives with hydrazine hydrate (80%) in methanol, unexpected reduction of theα-keto group occurred to affordN-acylamino acid hydrazide derivatives in good yield (80–90%) (Wolff-Kishner type reaction). All the synthesized compounds were characterized by1H NMR,13C NMR, and elemental microanalysis.

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