scholarly journals Alkoxyl-radical-mediated synthesis of functionalized allyl tert-(hetero)cyclobutanols and their ring-opening and ring-expansion functionalizations

2021 ◽  
Author(s):  
Yunxiao Zhang ◽  
Yizhi Zhang ◽  
Xiao Shen
Keyword(s):  
Ring Opening ◽  
Ring Expansion ◽  
Alkoxyl Radical

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.

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>

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.

Ring-Opening (ROP) versus Ring-Expansion (REP) Polymerization of ε-Caprolactone To Give Linear or Cyclic Polycaprolactones

2013 ◽  
Vol 46 (16) ◽  
pp. 6388-6394 ◽  
Author(s):  
José A. Castro-Osma ◽  
Carlos Alonso-Moreno ◽  
Joaquín C. García-Martinez ◽  
Juan Fernández-Baeza ◽  
Luis F. Sánchez-Barba ◽  
...  
Keyword(s):  
Ring Opening ◽  
Ring Expansion

1H-1,3-Diazepines and Ketenimines from Cyanotetrazolopyridines

2008 ◽  
Vol 61 (8) ◽  
pp. 592 ◽  
Author(s):  
Chris Addicott ◽  
Curt Wentrup
Keyword(s):  
Infrared Spectra ◽  
Ring Opening ◽  
Ring Expansion ◽  
Secondary Amines ◽  
Argon Matrix ◽  
The Matrix ◽  
Nitrogen Elimination ◽  
Isolated Species

Cyano-substituted tetrazolo[1,5-a]pyridines/2-azidopyridines 8T and 15T undergo thermal ring opening to the azides 8A and 15A. Solution photolysis causes nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 10 and 17, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines, with secondary amines to 2-dialkylamino-5H-1,3-diazepines, and with water to 1,3-diazepin-2-ones (12–14, 19, 21). Argon matrix photolysis of the azides affords the diazacycloheptatetraenes 10 and 17 as principal products together with ring-opened dicyanovinylketenimines 11 and 18. The matrix-isolated species were identified on the basis of comparison of the infrared spectra with those calculated at the B3LYP/6–31+G* level.

scholarly journals 4-Pyridylnitrene and 2-pyrazinylcarbene

2013 ◽  
Vol 9 ◽  
pp. 754-760 ◽  
Author(s):  
Curt Wentrup ◽  
Ales Reisinger ◽  
David Kvaskoff
Keyword(s):  
Ring Opening ◽  
Ring Expansion

Both flash vacuum thermolysis (FVT) and matrix photolysis generate 2-diazomethylpyrazine (22) from 1,2,3-triazolo[1,5-a]pyrazine (24). FVT of 4-azidopyridine (18) as well as of 24 or 2-(5-tetrazolyl)pyrazine (23) affords the products expected from the nitrene, i.e., 4,4’-azopyridine and 2- and 3-cyanopyrroles. Matrix photolyses of both 18 and 24 result in ring expansion of 4-pyridylnitrene/2-pyrazinylcarbene to 1,5-diazacyclohepta-1,2,4,6-tetraene (20). Further photolysis causes ring opening to the ketenimine 27.

scholarly journals Deployment of Aziridines for the Synthesis of Alkaloids and Their Derivatives

Synthesis ◽  
2019 ◽  
Vol 51 (07) ◽  
pp. 1491-1515 ◽  
Author(s):  
Matthias D’hooghe ◽  
Hyun-Joon Ha ◽  
Lingamurthy Macha
Keyword(s):  
Ring Opening ◽  
Ring Expansion ◽  
Ring Transformation ◽  
Aziridine Ring ◽  
Alkaloid Synthesis ◽  
Synthetic Intermediates ◽  
Synthetic Intermediate

Various (activated and non-activated) aziridines with diverse substitution patterns have been deployed successfully as starting materials for the synthesis of a wide variety of alkaloids via suitable functionalization and aziridine ring transformation. Alternatively, the preparation and interception of reactive aziridine intermediates has also been shown to constitute a valid approach toward alkaloid synthesis. This review summarizes aziridine-mediated syntheses of alkaloids, in which the aziridine is mobilized as either a substrate or an advanced synthetic intermediate.1 Introduction2 Alkaloids Synthesis from Aziridine Starting Materials2.1 (2R)- and (2S)-Hydroxymethyl-N-(1-phenylethyl)aziridines2.2 N-Benzylaziridine-2-carboxylates2.3 2-Substituted N-Tosyl- or N-Tritylaziridines2.4 2,3-Disubstituted N-Cbz- or N-Tosylaziridines2.5 N-DMB-aziridines3 Alkaloids Synthesis from Aziridines as Key Advanced Synthetic Intermediates3.1 Alkylative Aziridine Ring Opening3.2 Arylative Aziridine Ring Opening3.3 Ring Expansion3.4 Oxidative Aziridine Ring Opening3.5 Heteroatomic Nucleophilic Aziridine Ring Opening3.6 Reductive Aziridine Ring Opening4 Conclusion

Sign in / Sign up

Export Citation Format

Share Document