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.

Synthesis of Tricarbonyl(diacetylarene)chromium and Tricarbonyl(diformylarene)chromium Complexes

2002 ◽  
Vol 67 (11) ◽  
pp. 1616-1622 ◽  
Author(s):  
Iveta Kmentová ◽  
Štefan Toma
Keyword(s):  
Chromium Complexes ◽  
Acidic Hydrolysis ◽  
Protective Groups ◽  
Hydrolysis Of ◽  
Tricarbonylchromium Complexes

Tricarbonylchromium complexes of diacetylbenzenes and 2,2'-diacetylbiphenyl were prepared in reasonable yields by direct complexation of the starting materials. Tricarbonylchromium complexes of diformylbenzenes and 2,2'-diformylbiphenyl were prepared in good yields by the complexation of the corresponding dioxolanes followed by acidic hydrolysis of the protective groups.

scholarly journals Synthesis and Antiproliferative Activity of Phosphorus Substituted 4-Cyanooxazolines, 2-Aminocyanooxazolines, 2-Iminocyanooxazolidines and 2-Aminocyanothiazolines by Rearrangement of Cyanoaziridines

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4265
Author(s):  
Victor Carramiñana ◽  
Ana M. Ochoa de Ochoa de Retana ◽  
Francisco Palacios ◽  
Jesús M. de los de los Santos
Keyword(s):  
Ring Opening ◽  
Human Lung ◽  
Ring Expansion ◽  
Moderate Activity ◽  
A549 Cell Line ◽  
One Pot ◽  
Acidic Conditions ◽  
Lung Adenocarcinoma A549 ◽  
High Yields

Several phosphorus-substituted N-acylated cyanoaziridines 2 and N-carbamoylated cyanoziridines 5 were prepared in good to high yields. N-Acylated cyanoaziridines 2 were used, after ring expansion, in an efficient synthesis of oxazoline derivative 3a and in a completely regio-controlled reaction in the presence of NaI. Conversely, N-carbamoyl cyanoaziridines 5 reacted with NaI to obtain a regioisomeric mixture of 2-aminocyanooxazolines 7. Mild acidic conditions can be used for the isomerization of N-thiocarbamoyl cyanoaziridine 6a into a 2-aminocyanothiazoline derivative 8a by using BF3·OEt2 as a Lewis acid. Likewise, a one pot reaction of NH-cyanoaziridines 1 with isocyanates obtained 2-iminocyanooxazolidines 9 regioselectively. This synthetic methodology involves the addition of isocyanates to starting cyanoaziridines to obtain N-carbamoyl cyanoaziridines 5, which after the ring opening, reacts with a second equivalent of isocyanate to give the final 2-imino cyanooxazolidines 9. In addition, the cytotoxic effect on the cell lines derived from human lung adenocarcinoma (A549) was also screened. 2-Iminooxazolidines 9 exhibited moderate activity against the A549 cell line in vitro. Furthermore, a selectivity towards cancer cells (A549) over non-malignant cells (MCR-5) was detected.

Ring expansion and ring opening of 3-halooxindoles with N-alkoxycarbonyl-O-tosylhydroxylamines for divergent access to 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas

2021 ◽  
Author(s):  
Wei-Cheng Yuan ◽  
Jian Zuo ◽  
Shu-Pei Yuan ◽  
Jian-Qiang Zhao ◽  
Zhen-Hua Wang ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Expansion

The reaction of N-alkoxycarbonyl-O-tosylhydroxylamines with indol-2-ones in situ generated from 3-halooxindoles has been developed for divergently accessing 4-aminoquinolin-2-ones and N-Cbz-N’-arylureas in good to excellent yields.

6π-Tricarbonyl-Komplexe von Pyridin-Derivaten, Synthesen und Reaktionen / 6π-Tricarbonyl-Chromium Complexes of Pyridine Derivatives, Syntheses and Reactions

1984 ◽  
Vol 39 (2) ◽  
pp. 207-212 ◽  
Author(s):  
Karl Dimroth ◽  
Rüdiger Thamm ◽  
Hans Kaletsch
Keyword(s):  
Hydrogen Atom ◽  
Phosphorus Atom ◽  
Nmr Spectra ◽  
Pyridine Derivatives ◽  
Chromium Complexes ◽  
X Ray ◽  
Chromium Hexacarbonyl ◽  
Allyl Rearrangement ◽  
Tricarbonylchromium Complexes ◽  
C Nmr

New 6π-tricarbonylchromiumpyrnftne complexes 5c and 5d could be synthesized from 2,6-di-rbutyl- and 2,4,6-tri-f-butylpyridines (3c and 3d) with chromium hexacarbonyl. They are characterized by their 1H and 13C NMR Spectra and their CO-frequencies which are rather similar to those of 6π-tricarbonylchromium-2,4 ,6-triphenyl [1] or 2,4,6-trw-butyl- [2] λ3-phosphorins. When 5d is reacted with lithiumphenyl, the phenyl residue adds to C-4, giving probably compound 7, which by methanolysis and allyl rearrangement of the hydrogen atom from position 4 to position 2 affords tricarbonylchromium-2,6-di-f-butyl-4-phenyl-1,2-dihydropyridine (8) in 56% yield. The 6π-tricarbonylchromium complexes of 2,4,6-triphenyl- or 2,4,6-tn-t-butyl-λ3-phosphorins react with lithiumorganic compounds by addition only to the phosphorus atom whose reaction with methyliodide lead to tricarbonylchromium-λ5-phosphorin-ylid complexes [2], 5 d is a well crystallized compound, the X-ray analysis of the first 6π-tricarbonylchromium pyridine derivate could be performed [3] and compared with the results of the X-ray analysis of 6π-tricarbonylchromiumx 2,4,6-triphenyl-λ3-phosphorin [4]

scholarly journals Heck-Type Coupling of Fused Bicyclic Vinylcyclopropanes: Synthesis of 1,2-Dihydropyridines, 2,3-Dihydro-1H-Azepines, 1,4-Cyclohexadienes, 2H-Pyrans, and 1,3-Butadienes

2021 ◽  
Author(s):  
Nikolai Wurzer ◽  
Urszula Klimczak ◽  
Tobias Babl ◽  
Sebastian Fischer ◽  
Ricardo A. Angnes ◽  
...  
Keyword(s):  
Heck Reaction ◽  
Ring Opening ◽  
Theoretical Calculations ◽  
Ring Expansion ◽  
Mechanistic Studies ◽  
Type Coupling ◽  
Hydride Elimination ◽  
Unexpected Behavior

Herein, we report a versatile approach for the endocyclic ring-opening of bicyclic vinylcyclopropanes triggered by Heck arylations. Key step for this transformation is a [1,3]-migratory shift of Pd allowing the ring expansion of cyclopropanated pyrroles, piperidines, furans as well as cyclopentadienes to grant access to the corresponding 1,2-dihydropyridines, 2<i>H</i>-pyrans, 2,3-dihydro-1<i>H</i>-azepines and 1,4-cyclohexadienes, respectively. Additionally, <i>gem</i>-disubstituted cyclopropanated furans showed unexpected behavior by giving diastereoselectively asymmetrically substituted dienes. Mechanistic studies and theoretical calculations point towards a facile [1,3]-migratory shift of Pd along the cyclopropane moiety, which can successfully compete with the usual termination step of a Heck reaction via a <i>syn</i>-b-hydride elimination.<br>

Synthesis of Symmetrical Dipurine-Nucleoside Diphosphates from the Corresponding Nucleoside Phosphoropiperidates

2014 ◽  
Vol 1023 ◽  
pp. 55-58
Author(s):  
Xiao Chuan Li ◽  
Shan Shan Gong ◽  
Qi Sun
Keyword(s):  
Efficient Method ◽  
Good Yield ◽  
Purine Bases ◽  
Hydrolysis Of

A general and efficient method for the preparation of symmetrical dinucleoside diphosphates with purine bases has been developed. Ap2A and Gp2G were synthesized from the in situ hydrolysis of corresponding nucleoside 5′-phosphoropiperidates with 4,5-dicyanoimidazole as the activator. This method features easily accessible starting materials, simple procedures, and good yield.

Superhydrophobic functionalization of cutinase activated poly(lactic acid) surfaces

2017 ◽  
Vol 19 (3) ◽  
pp. 816-822 ◽  
Author(s):  
A. Ortner ◽  
A. Pellis ◽  
C. Gamerith ◽  
A. Orcal Yebra ◽  
D. Scaini ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Enzymatic Hydrolysis ◽  
Ring Opening ◽  
Superhydrophobic Surfaces ◽  
Poly Lactic Acid ◽  
Hydrolysis Of

Controlled enzymatic hydrolysis of PLA surfaces, followed by ring opening of AKD, leads to superhydrophobic surfaces (WCA >150°).

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.

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