An unexpected thermal-ring-rearrangement of benzochromenes to inden-3-yl-naphthols with pTsOH

2018 ◽  
Vol 16 (42) ◽  
pp. 7920-7925 ◽  
Author(s):  
Srinivasarao Yaragorla ◽  
Tabassum Khan
Keyword(s):  
Ring Opening ◽  
Ring Closure ◽  
Acid Catalysts ◽  
First Report

Described here is the first report of an unexpected thermal-ring rearrangement (TRR) of benzochromenes to indene derivatives promoted by pTsOH, which proceeds through the protonation of benzochromenes by an acid catalysts followed by ring-opening and ring-closure by an intramolecular Friedel–Crafts cyclization.

First Total Synthesis of a Fluorinated Calystegin

2010 ◽  
Vol 65 (4) ◽  
pp. 445-451 ◽  
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.

ChemInform Abstract: Synthesis of Functionalized Cyclophanes by Ring-Opening/Ring-Closure Cascade Reactions of Siloxycyclopropanes.

ChemInform ◽  
2010 ◽  
Vol 30 (21) ◽  
pp. no-no
Author(s):  
Astrid Ullmann ◽  
Margit Gruner ◽  
Hans-Ulrich Reissig
Keyword(s):  
Ring Opening ◽  
Cascade Reactions ◽  
Ring Closure

ChemInform Abstract: Ring Opening Ring Closure Reactions with 3-Substituted Chromones under Nucleophilic Conditions

ChemInform ◽  
2015 ◽  
Vol 46 (50) ◽  
pp. no-no
Author(s):  
Magdy A. Ibrahim ◽  
Nasser M. El-Gohary ◽  
Sara Said
Keyword(s):  
Ring Opening ◽  
Ring Closure

Furan Ring Opening—Isochromene Ring Closure: A New Approach to Isochromene Ring Synthesis.

ChemInform ◽  
2006 ◽  
Vol 37 (11) ◽  
Author(s):  
Alexander V. Butin ◽  
Valdimir T. Abaev ◽  
Vladimir V. Mel'chin ◽  
Artem S. Dmitriev
Keyword(s):  
Ring Opening ◽  
Furan Ring ◽  
Ring Closure ◽  
New Approach ◽  
Ring Synthesis

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

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.

scholarly journals Mono- and bithiophene-substituted diarylethene photoswitches with emissive open or closed forms

2019 ◽  
Vol 15 ◽  
pp. 2344-2354 ◽  
Author(s):  
A Lennart Schleper ◽  
Mariano L Bossi ◽  
Vladimir N Belov ◽  
Stefan W Hell
Keyword(s):  
Visible Light ◽  
Single Molecule ◽  
Ring Opening ◽  
Uv Light ◽  
Visible Region ◽  
Super Resolution ◽  
Ring Closure ◽  
Low Emission ◽  
Fluorescence Modulation ◽  
High Degree

We present a new series of photochromic 1,2-bis(2-ethylbenzo[b]thiophen-3-yl)perfluorocyclopentenes with an oxidized benzothiophene core (O) or a nonoxidized one, decorated with mono- (Th1) and bithiophene (Th2) units attached to positions 6 and 6′ (Sy = symmetric) or only to position 6 (As = asymmetric). “Oxidized” compounds have highly fluorescent closed forms emitting in the visible region (yellow to red). The dyes with nonoxidized benzothiophenes possess fluorescent open forms with rather low emission efficiency. The photoswitching kinetics was studied at several wavelengths with UV and visible light. New diarylethenes underwent ring-closure reactions by irradiation with UV light (365 nm, 405 nm), and the reversible ring-opening by irradiation with visible light (470 nm, 530 nm). The on-switching of fluorescence due to the ring-closure reaction was observed also with visible light of 470 nm (to an extent of 10% for compound SyOTh 1 ) and attributed to the Urbach tail effect. Due to a high degree of fluorescence modulation (>270), good fatigue resistance and large fluorescence quantum yield, compound SyOTh 1 emerged as a candidate for single-molecule based super-resolution fluorescence microscopy.

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