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Electrophilic substitutions by 2,2-bis(trifluoromethyl)ethylene-1,1-dicarbonitrile via addition

✍ Scribed by Reinhard Brückner; Rolf Huisgen

Publisher
Elsevier Science
Year
1991
Tongue
French
Weight
270 KB
Volume
32
Category
Article
ISSN
0040-4039

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✦ Synopsis

The interaction of the title compound (BTF) with unsaturated nucleophiles (ketene dithioacetals, a-substituted vinyl ethers, N-vinylcarboxamides, enols, furans, N-methylpyrrole, N-methylindole) effects substitution of vinylic or aromatic H by -C(CF3)2-CH(CN)2.

The highly electrophilic 2,2-bis(trifluoromethyl)ethylene-1 ,l -dicarbonitrile (BTF) 2 converts nucleophilic unsaturated compounds into carbocationic intermediates by two ways, either addition to the double bond furnishing a 1,4 zwitterion, 1 + 2, or by hydride -'@&action giving rise to an allylic ion pair, 7 + 3.

The 1,Czwitterion 2 may cyclize to the cyclobutane 3 as observed for enol ethers (X = OR) or thioenol ethers (X = SR) 3,4 whereas 1,3 or 1,5 prototropy leads to substitution products without or with shift of the double bond (4, 5). The formation of a type 5 product from a-methylstyrene and BTF 5 presumedly offers an example for the 1,5-H shift of zwitterion 2 (X = CSH5). Alternatively, the full development of charges in reactions 2 -+ 5, i. e., the intermediacy of zwitterion 2, can be circumvented 7a

📜 SIMILAR VOLUMES

Substitutions and dehydrogenations by 2,
Substitutions and dehydrogenations by 2,2-bis(trifluoromethyl)-ethylene-1,1-dicarbonitrile via hydride abstraction
✍ Reinhard Brückner; Rolf Huisgen 📂 Article 📅 1991 🏛 Elsevier Science 🌐 French ⚖ 291 KB

Substitution of benzylic H by the title compound (BTF) gives rise to products with -CH(CF3)2 terminus exclusively; an intermediate benzylic ion pair results from hydride transfer. Instead of ion recombination, proton transfer may be the concluding step generating dehydrogenation products and 2,2-bis

2,2-bis(trifluoromethyl)ethylene-1,1-dic
2,2-bis(trifluoromethyl)ethylene-1,1-dicarbonitrile and styrenes the concertedness of the [2 + 4] cycloaddition
✍ Reinhard Brückner; Rolf Huisgen 📂 Article 📅 1990 🏛 Elsevier Science 🌐 French ⚖ 265 KB

The effects of substituents and solvent variation on the rate constants are in harmony with a concerted cycloaddition. In the preceding communication we described reactions of 2,2-bis(trifluoromethyl)ethylene-1 ,I-dicarbonitrile (BTF; 1) with styrenes 2 2. By rapid reversible Diels-Alder additions w