ChemInform Abstract: Three-Membered Ring Opening in Perfluoro-1,1a,6,6a-tetrahydrocyclopropa[a]indene and Its 1a-Trifluoromethyl Derivative under the Action of SbF5.

Highly functionalized and annulated 2,4-cyclooctadienones are formed in a stereoselective manner by sequential treatment of squarate esters with a lithiated enecarbamate (six-membered ring or larger) and a cycloalkenyl- or 1-alkenyllithium reagent. The mechanistic details of this multistep process are presented. Particular attention is drawn to the step that involves intramolecular nucleophilic attack by a proximal oxido anion at the carbamate carbonyl and results in redirection of the cascade. This step is thwarted when five-membered cyclic enecarbamates are employed because of the excessive buildup of ring strain in the associated transition state.Key words: squarate esters, enecarbamates, conrotatory ring opening, intramolecular acylation, alkenyllithium reagents.

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ChemInform Abstract: REGIO- AND STEREOSELECTIVITY OF THE 3-MEMBERED RING OPENING OF SOME 3,4-EPOXYTETRAHYDROPYRANS AND OF THE CORRESPONDING EPIBROMIUM IONS

Chemischer Informationsdienst ◽

10.1002/chin.197507214 ◽

1975 ◽

Vol 6 (7) ◽

pp. no-no

Author(s):

G. BERTI ◽

G. CATELANI ◽

M. FERRETTI ◽

L. MONTI

Keyword(s):

Ring Opening ◽

Membered Ring

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ChemInform Abstract: Five- and Six-Membered Ring Opening of Pyroglutamic Diketopiperazine.

ChemInform ◽

10.1002/chin.200234221 ◽

2010 ◽

Vol 33 (34) ◽

pp. no-no

Author(s):

Dennis A. Parrish ◽

Lon J. Mathias

Keyword(s):

Ring Opening ◽

Membered Ring

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Unravelling the Mechanism and Selectivity of the NHC‐catalyzed Three‐Membered Ring‐Opening/Fluorination of Epoxy Enals: A DFT Study

ChemCatChem ◽

10.1002/cctc.201900424 ◽

2019 ◽

Vol 11 (12) ◽

pp. 2919-2925 ◽

Cited By ~ 13

Author(s):

Yang Wang ◽

Ling‐Bo Qu ◽

Yu Lan ◽

Donghui Wei

Keyword(s):

Ring Opening ◽

Membered Ring ◽

Dft Study

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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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An Unexpected Synthesis of Novel Oxygen-Bridged 1,5-Benzothiazepine Derivatives and their Reductive Five-Membered-Ring Opening

Monatshefte für Chemie - Chemical Monthly ◽

10.1007/s007060050320 ◽

2000 ◽

Vol 131 (4) ◽

pp. 0393-0400 ◽

Cited By ~ 6

Author(s):

Roshan Ahmad ◽

Mohammad Zia-ul-Haq ◽

Shahid Hameed ◽

Humaira Akhtar ◽

Helmut Duddeck

Keyword(s):

Ring Opening ◽

Membered Ring

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Synthesis of Four-Membered Ring Spiro-β-lactams by Epoxide Ring-Opening.

ChemInform ◽

10.1002/chin.200743104 ◽

2007 ◽

Vol 38 (43) ◽

Author(s):

Fides Benfatti ◽

Giuliana Cardillo ◽

Luca Gentilucci ◽

Alessandra Tolomelli

Keyword(s):

Ring Opening ◽

Membered Ring ◽

Epoxide Ring ◽

Epoxide Ring Opening

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Biotransformation of Glabratephrin, a Rare Type of Isoprenylated Flavonoids, by Aspergillus niger

Zeitschrift für Naturforschung C ◽

10.1515/znc-2008-7-816 ◽

2008 ◽

Vol 63 (7-8) ◽

pp. 561-564 ◽

Cited By ~ 5

Author(s):

Abou-El-Hamd H Mohamed ◽

Ali K. Khalafallah ◽

Afifi H. Yousof

Keyword(s):

Aspergillus Niger ◽

Ring Opening ◽

Microbial Transformation ◽

Membered Ring ◽

Nmr Studies ◽

Rare Type ◽

Tephrosia Purpurea ◽

Isolated Compound

Microbial transformation of glabratephrin, the major isolated compound from Tephrosia purpurea, afforded pseudosemiglabrin. The formation of the transformed compound seems to be performed via ring opening-closure of a five-membered ring causing transformation from a spiro into a fused system. The structure of the transformed compound was determined by comprehensive NMR studies, including DEPT, COSY, HMQC, NOE and MS.

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