Synthetic Exploitation of Halogenated Alkenes Containing Electron-Withdrawing Group (EWG): Access to Valuable 2,4-Dinitrothiophenes via Ring-Closing and Ring-Opening/Ring-Closing Protocols

Heterocycles ◽  
2013 ◽  
Vol 87 (12) ◽  
pp. 2589 ◽  
Author(s):  
Amac Fatih Tuyun
Keyword(s):  
Ring Opening ◽  
Halogenated Alkenes ◽  
Electron Withdrawing Group

Regioselectivity and Reactivity of Intramolecular [2+2] Cycloaddition Reactions of Acyl Ketenes: Experimental and Theoretical Studies

Synlett ◽  
2018 ◽  
Vol 29 (14) ◽  
pp. 1836-1841 ◽  
Author(s):  
Mahboobeh Zahedifar ◽  
Hassan Sheibani ◽  
Vahid Saheb
Keyword(s):  
Ring Opening ◽  
Density Functional ◽  
Cycloaddition Reaction ◽  
Density Functional Theory Calculations ◽  
Theoretical Studies ◽  
Aryl Group ◽  
Functional Theory ◽  
Electron Withdrawing Group ◽  
Experimental And Theoretical Studies ◽  
Mechanism Of The Reaction

The regioselectivity of the intramolecular [2+2] cycloaddition reaction of acyl ketenes formed from metastable mesoionic 1,3-oxazinium-4-olates was investigated by experimental and theoretical methods. The ring opening of the mesoionic N-allyl-2-(2-arylvinyl)-1,3-oxazinium-4-olates led to the formation of unstable acyl ketenes. ­Although there are four possible paths for an intramolecular [2+2] cyclo­addition reaction involving the two double bonds (vinyl and allyl), only the intramolecular [2+2] criss-cross cycloaddition reaction through the vinyl double bond occurred to give 3-allyl-3-azabicyclo[3.1.1]heptane-2,4,6-trione derivatives. These products were not formed when a strongly electron-withdrawing group was present on the aryl group of acrylamides or benzamides. To understand the mechanism of the reaction, density functional theory calculations at the M06-2X/6-31+G(d) level were performed. These revealed that the formation of some preliminary intermediates plays a significant role in the formation of mesoionic 1,3-oxazinium-4-olates.

Amino-functional polyethers: versatile, stimuli-responsive polymers

2020 ◽  
Vol 11 (24) ◽  
pp. 3940-3950 ◽  
Author(s):  
Patrick Verkoyen ◽  
Holger Frey
Keyword(s):  
Ring Opening ◽  
Review Article ◽  
Stimuli Responsive ◽  
New Class ◽  
Stimuli Responsive Polymers ◽  
Responsive Polymers

Amino-functional polyethers have emerged as a new class of “smart”, i.e. pH- and thermoresponsive materials. This review article summarizes the synthesis and applications of these materials, obtained from ring-opening of suitable epoxide monomers.

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