Intermediates from ring-opening reactions. Reactions of 2-chloro-5-nitropyridine and 2-chloro-3-nitropyridine with deuteroxide ion in selected solvents

Open chain intermediates from the ring-opening reaction of aqueous sodium deuteroxide (2 mol) with 2-chloro-5-nitropyridine (1 mol) and 2-chloro-3-nitropyridine (1 mol) were isolated. These intermediates were purified, analyzed for elemental composition, and characterized by various spectrophotometric techniques. The intermediate formed from 2-chloro-5-nitropyridine and two equivalents of deuteroxide ion reacts with additional deuteroxide in D2O in various polar solvents to reclose the pyridine ring. The kinetics of the ring closure reaction are reported and are supplemented with observations of salt and solvent effects upon the rate of closure. In addition, a mechanism for the ring closure is presented. The intermediate formed from 2-chloro-3-nitropyridine did not undergo a similar ring closure when reacted with additional deuteroxide, but instead formed various decomposition products. A reason for the failure of this ring closure is suggested.

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Kinetische Analyse zur Umwandlung von Oxirenen oder Thiirenen und ihren offenkettigen Valenzisomeren / Kinetic Analysis for the Conversion of Oxirenes or Thiirenes and their Open-Chain Valence Isomers

Zeitschrift für Naturforschung B ◽

10.1515/znb-1980-0822 ◽

1980 ◽

Vol 35 (8) ◽

pp. 1040-1048 ◽

Cited By ~ 6

Author(s):

Herbert Meier ◽

Heinz Kolshorn

Keyword(s):

Experimental Data ◽

Kinetic Models ◽

Ring Opening ◽

Product Distribution ◽

Ring Closure ◽

Quantitative Interpretation ◽

Open Chain ◽

Energy Profiles ◽

Ring Opening Reactions ◽

Kinetische Analyse

Abstract Ring closure and ring opening reactions possess an outstanding significance for the formation and reactivity of antiaromatic heterocycles like oxirenes and thiirenes. The valence isomerisations 2 ⇆ 1 ⇆ 2' can be controlled by the product distribution 2 → P/2' → P'. A quantitative interpretation of many experimental data, published in the last years, is given on the basis of a few kinetic models, which consider thermal and photochemical pathways. Possible energy profiles of single hypersurfaces (S0 or S1) and the transition between different hypersurfaces (S1 → S0) are the most important features of these models.

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First Total Synthesis of a Fluorinated Calystegin

Zeitschrift für Naturforschung B ◽

10.1515/znb-2010-0402 ◽

2010 ◽

Vol 65 (4) ◽

pp. 445-451 ◽

Cited By ~ 5

Author(s):

René Csuk ◽

Erik Prell ◽

Stefan Reißmann ◽

Claudia Korb

Keyword(s):

Total Synthesis ◽

Ring Opening ◽

Competitive Inhibitor ◽

Ring Closure ◽

Target Compound ◽

Metathesis Reaction ◽

Grubbs Catalyst ◽

Ring Opening Reaction ◽

Ultrasound Assisted ◽

Key Steps

A straightforward chiral pool synthesis for the first fluorinated calystegin is described. Key steps of this synthesis include an ultrasound-assisted Zn-mediated tandem ring opening reaction followed by a Grubbs’ catalyst-mediated ring closure metathesis reaction. The target compound is a selective and competitive inhibitor for a β -glycosidase.

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One-Pot Synthesis of Novel Dibenzoxanthenes, Diarylbutanes, and Calix[4]resorcinarenes via Consecutive Pyrrolidine Ring-Closure/Ring-Opening Reactions

Journal of Chemistry ◽

10.1155/2019/3424319 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Andrey V. Smolobochkin ◽

Almir S. Gazizov ◽

Alexander R. Burilov ◽

Michail A. Pudovik

Keyword(s):

Ring Opening ◽

Ring Closure ◽

Acidic Media ◽

Pyrrolidine Ring ◽

One Pot ◽

One Pot Synthesis ◽

Ring Opening Reactions

Herein, we report the approach to the otherwise hardly accessible dibenzoxanthenes, diarylbutanes, and calix[4]resorcinarenes possessing urea moieties based on the reaction of N-(4,4-diethoxybutyl)ureas with electron-rich aromatics in strongly acidic media. Unlike the previously developed methods, the proposed approach benefits from one-pot procedure and allows to obtain the target compounds with much higher yields.

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Thermal intramolecular reactions of Δ1-1,2,4-triazolines with extended exocyclic unsaturation

Canadian Journal of Chemistry ◽

10.1139/v88-067 ◽

1988 ◽

Vol 66 (3) ◽

pp. 385-390 ◽

Cited By ~ 2

Author(s):

Adrian L. Schwan ◽

John Warkentin

Keyword(s):

Ring Opening ◽

Hydrolysis Product ◽

Sigmatropic Rearrangement ◽

Membered Ring ◽

Ring Closure ◽

Experimental Results ◽

First Order ◽

Ring Opening Reaction ◽

Intramolecular Reactions

Fumaratotriazoline (1) and amidotriazoline (3) undergo thermal first-order transformations in solution at 65 °C. The former affords the isomeric pyrrole 5 and its hydrolysis product 6. A mechanism involving opening of the initial five-membered ring to form 8, followed by closure to a new five-membered ring (9), is proposed. Amidotriazoline (3) loses N2 on heating to form 19. The experimental results are best accommodated in terms of a novel mechanism involving an electrocyclic ring closure, a [3 + 2] cycloreversion to form an ylide, a sigmatropic rearrangement of the ylide, and, finally, an electrocyclic ring-opening reaction.

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ChemInform Abstract: ANOMERIZATION OF FURANOSE SUGARS: KINETICS OF RING-OPENING REACTIONS BY PROTON AND CARBON-13 SATURATION-TRANSFER NMR SPECTROSCOPY

Chemischer Informationsdienst ◽

10.1002/chin.198244101 ◽

1982 ◽

Vol 13 (44) ◽

Author(s):

A. S. SERIANNI ◽

J. PIERCE ◽

S.-G. HUANG ◽

R. BARKER

Keyword(s):

Nmr Spectroscopy ◽

Ring Opening ◽

Saturation Transfer ◽

Ring Opening Reactions ◽

Kinetics Of

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Synthetic and Theoretical Studies of Novel Ring Closure and Ring Opening Reactions

ChemInform ◽

10.1002/chin.200640271 ◽

2006 ◽

Vol 37 (40) ◽

Author(s):

Jose Sepulveda-Arques ◽

M. Eugenia Gonzalez-Rosende

Keyword(s):

Ring Opening ◽

Ring Closure ◽

Theoretical Studies ◽

Ring Opening Reactions

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Torquoselectivity of the Ring-Opening Reaction of 3,3-Dihalosubstituted Cyclobutenes: Lone Pair Repulsion and Cyclic Orbital Interaction

10.26434/chemrxiv.9178121.v2 ◽

2019 ◽

Author(s):

Yuji Naruse ◽

Atsushi Takamori

Keyword(s):

Double Bond ◽

Ring Opening ◽

Lone Pair ◽

Repulsive Interaction ◽

Orbital Interaction ◽

Ring Opening Reaction ◽

Ring Opening Reactions ◽

Major Factors ◽

Vacant Orbital ◽

Model Reactions

<div><div>Three major factors determine torquoselectivity, which is the diastereoselectivity in electrocyclic ring-opening reactions to produce <i>E</i>/<i>Z</i>-double bond(s). One is the interaction between the decomposing s<sub>CC</sub> bond and low-lying vacant orbital(s), such as a p*- or s*-orbital on the substituent, which promotes the reaction, resulting in inward rotation of the substituent. Second, for a substituent with a lone pair(s), repulsive interaction between the decomposing s-bond and the lone pair(s) hinders inward rotation, so that the products of outward rotation should be preferred. Finally, a more strongly donating s-electron-donating group (sEDG) rotates inwardly due to stabilization by phase-continuous cyclic orbital interaction. We compared the latter two interactions, repulsion between the lone pairs on the substituent and stabilization from phase-continuous cyclic orbital interaction, to determine which has a greater effect on the diastereoselectivity. We considered a series of model reactions with halogen substituents, and concluded that the diastereoselectivity is mainly controlled by cyclic orbital interaction.<br></div></div>

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Asymmetric ring-opening reaction of meso-epoxides with aromatic amines using homochiral metal–organic frameworks as recyclable heterogeneous catalysts

RSC Advances ◽

10.1039/c8ra05163a ◽

2018 ◽

Vol 8 (49) ◽

pp. 28139-28146 ◽

Cited By ~ 8

Author(s):

Koichi Tanaka ◽

Maya Kinoshita ◽

Jun Kayahara ◽

Yutaro Uebayashi ◽

Kazusada Nakaji ◽

...

Keyword(s):

Aromatic Amines ◽

Ring Opening ◽

Heterogeneous Catalysts ◽

Metal Organic Framework ◽

Metal Organic Frameworks ◽

Amino Alcohols ◽

Ring Opening Reaction ◽

Ring Opening Reactions ◽

Metal Organic ◽

Asymmetric Ring Opening

Asymmetric ring-opening reactions of meso-epoxides by aromatic amines were achieved by using some chiral metal–organic frameworks. The corresponding β-amino alcohols were obtained with good yields and enantioselectivities (up to 97% ee).

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