Perfluoro-4-methyl-2-pentene, reaction with

Perfluoro-2 (1 ethyl 1 methylpropyl)-3-methyl-l-pentene, the major hex-amer of tetrafluoroethylene, reacts with sodium methoxide to yield an ester, whereas a stable crowded ketene is formed by reaction with sodium hydroxide [2d] (equation 23)... 

Flowers et al.164 reacted perfluoro-2-methyl-2-pentene with 2-aminopyri-dine or 2-amino-4-methylpyridine in tetrahydrofuran at room temperature to obtain the pyrido[1.2-u]pyrimidines (95). Reaction with 2-amino-6-methylpyridine yielded the 1,8-naphthyridine (96). 

It has been reported that condensation of perfluoro-2-methyl-2-pentene 6 with hydrazones [4], arylhydrazines and propionylhydrazine [5] in basic media (NaaCOs or EtsN), lead to 5-fluoropyrazole derivatives as single products in good to excellent yield. However, a study carried out by Furin and co-workers [6] using 6 and a variety of arylhydrazines, in the presence of triethylamine, showed that, in all cases, mixtures of 3- and 5-fluoropyrazole derivatives 7 and 8 (Scheme 3) were obtained. The regioisomeric ratios were dependent on the reaction conditions and arylhydrazine used. Two different reaction pathways were proposed for explaining these results. 

Reactions of fluorinated dipolarophiles. Electron-deficient unsaturated species generally make better dipolarophiles, therefore, fluonnated alkenes become better dipolarophiles when vinylic fluonnes are replaced by perfluoroalkyl groups For example, perfluoro-2-butene is unreactive with diazomethane, but more highly substituted perfluoroalkenes, such as perfluoro-2-methyl-2-pentene, undergo cycloadditions in high yields [5] (equation 2) Note the regiospecificity that IS observed in this reaction... 

It was assumed (90JFC(48)133, 87IZY957) that perfluoro-2,4,4-trimethyl-3-isopropyl-2-thiete 28 is produced by the reaction of isomeric perfluoro-3-isopropyl-2-methyl-2-pentene with tert-butylmercaptan in the presence of triethylamine, which takes place by intramolecular cyclization of the S-nucleophile at the carbon atom of the CF fragment. 

The reaction of perfluoro-4-methyl-2-pentene with ethylene glycol also leads to 2-fluoro-2-trifluoromethyl-3-(2,2,2-trifluoro-1 -trifluoromethylethy-lidene)-l,4-dioxane 106 (96ZOB1995). The formation of the six-membered heterocycle occurs via generation of the intermediate carbanion and fluoride ion elimination from the y-position. Subsequent intramolecular nucleophilic cyclization involving the O-nucleophilic center and the internal double bond leads to a 1,4-dioxane derivative (route e). 

An unusually stable alkyl radical 1 was discovered in 1985. The radical was isolated in the course of the reaction of fluorine gas with perfluoro 3-isopropyl-4-methyl-2-pentene and 3 - ethyl-2,4- dimethyl-2-pentene at ambient temperature [ 1 ]. The radical 1 is stable at room temperature to dimerization, disproportionation, treatments with 02, Cl2, Br2, I2, or aqueous acid and base, and even heating at 70°C in GC. It only decomposes by elimination of a trifluoromethyl radical through (3-scission on heating at 100°C, with a half-life of 60 min. 

While the reactions of perfluoro-2-methyl-2-pentene with 2-aminopyridine or its 4-methyl derivative furnished 2-pentafluoroethyl-3-trifluoromethyl-4-(2-pyridyl)imino-derivatives of (12) that with... 

Snegirev, V.F. Makarov, K.N. Reaction of perfluoro-2-methyl-2-pentene with bifunctional nucleophiles. Izv. Akad. Nauk SSSR, Ser. Khim. 1985, (9), 2066-2076. 

Snegirev, V.F. Antipin, M.Y. Khrustalev, V.N. Struchkov, YT. Reaction of perfluoro-2-methyl-2-pentene with cycloalkanone oximes. New examples of the Beckmann-Chap-man rearrangement. Izv. Akad. Nauk SSSR, Ser. Khim. 1994, (6), 1073-1077. Rauscher, W.H. Tucker, H. The synthesis of ethyl adipamate and 2-oxo-6,6-dihydroper-fluorohexamethylenimine. 7. Am. Chem. Soc. 1954, 76, 3599-3601. 

PerfluoroaIkyl-5-substituted-l//-pyrazoles 61 can be obtained in excellent yields by reaction of either perfluoroalkylacetylenes 59 [31] or A -aryl per(poly) fluoroalkyl phenyl acetylenic imines 60 [32] with hydrazine hydrate in EtOH (Scheme 18). The loss of two molecules of hydrogen fluoride in the former case, and arylamine in the latter, led to the final products. As it has been mentioned above, this strategy can be also applied for the preparation of polyfluorinated derivatives (see Scheme 3), by reaction of perfluoro-2-methyl-2-pentene with hydrazones [4] or arylhydrazines [5, 6] in a basic medium. 

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