596113-47-2Relevant academic research and scientific papers
Method for constructing four-membered ring through visible light catalytic [2+2] reaction
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Paragraph 0103-0105, (2018/11/03)
The invention discloses a method for constructing a four-membered ring through visible light catalytic [2+2] reaction. The method comprises the following steps: 1.1) adding an unsaturated double-bondcompound and a photosensitizer into a solvent to obtain a solution A; 1.2) irradiating the solution A by using visible light under the argon atmosphere to obtain a dimerized[2+2]cyclobutane product; or 2.1) adding the unsaturated double-bond compound, a styrene compound and the photosensitizer into a solvent to obtain a solution B; and 2.2) irradiating the solution B by using visible light under the argon environment to obtain a crossed [2+2]cyclobutane product. The visible light sensitizer is utilized for the first time and non-rigid double-bond intermolecular[2+2]cyclization reaction is realized; the use amount of the light sensitizer is small, the reaction can be realized under the argon environment by utilizing the visible light or sunlight, and the reaction condition is mild; and thewhole process is simple and efficient, and potential application in organic reaction and industrial production is embodied.
Trapping Tetramethylene Biradical Intermediates in Cycloaddition Reactions of p-Methoxystyrene by Vinyl Copolymerization Reactions
Hall, H.K.,Abdelkader, M.
, p. 2948 - 2953 (2007/10/02)
Tetramethylene biradical intermediates in cycloaddition reactions of p-methoxystyrene (1) with trimethyl ethylenetricarboxylate (2) at 70 - 116 deg C and dimethyl cyanofumarate (10) at 28 deg C were detected through the formation of aternating 1:1 copolymers 5 and 11, identical with those formed by deliberate free-radical-initiated copolymerizations of these monomers.The rates were insensitive to solvent polarity.Free-radical inhibitors supressed copolymerization and led instead to cycloadducts, dihydropyrans 3 and 12, respectively, pointing to common intermediates incopolymerization and cycloaddition.Heating the kinetically favored dihydropyran 3 isomerized it to 1-butene 4.Vacuum distillation of 3 gave 1 and 2, while similar treatment of 12 gave copolymer by cycloreversion and spontaneous copolymerization.An ion-radical mechanism was excluded because deliberate generation of 1+. in presence of 2 gave cyclodimer 8 or homopolymer 7.Reaction of 1 with tetramethyl ethylenetetracarboxylate (14), which cannot copolymerize, led to cyclobutane 15 and traces of homopolymer 7 (some zwitterion character).The reactivity sequence 10 > 2 > 14 is dictated largely by resonance stabilization of and steric hindrance to tetramethylene formation.Consideration of the conformations available to tetramethylenes 16 - 18 provides a reasonable explanation of the results.
