Electrocyclic reactions fluorine

Diels-Alder reactions, 4, 842 flash vapour phase pyrolysis, 4, 846 reactions with 6-dimethylaminofuKenov, 4, 844 reactions with JV,n-diphenylnitrone, 4, 841 reactions with mesitonitrile oxide, 4, 841 structure, 4, 715, 725 synthesis, 4, 725, 767-769, 930 theoretical methods, 4, 3 tricarbonyl iron complexes, 4, 847 dipole moments, 4, 716 n-directing effect, 4, 44 2,5-disubstituted synthesis, 4, 116-117 from l,3-dithiolylium-4-olates, 6, 826 electrocyclization, 4, 748-750 electron bombardment, 4, 739 electronic deformation, 4, 722-723 electronic structure, 4, 715 electrophilic substitution, 4, 43, 44, 717-719, 751 directing effects, 4, 752-753 fluorescence spectra, 4, 735-736 fluorinated derivatives, 4, 679 H NMR, 4, 731 Friedel-Crafts acylation, 4, 777 with fused six-membered heterocyclic rings, 4, 973-1036 fused small rings structure, 4, 720-721 gas phase UV spectrum, 4, 734 H NMR, 4, 7, 728-731, 939 solvent effects, 4, 730 substituent constants, 4, 731 halo... 

Diazocines are isolated, as byproducts, in another photochemical reaction which starts from fluorinated pyridazines. On irradiation of 6 a Dewar diazabenzene derivative is formed, via an electrocyclic ring closure, which looses a fluorinated nitrile to give the azacyclobutadiene system 7. This reactive intermediate then leads vide supra) to the 1,5-diazocine 8.50... 

Results of studies of the electrocyclic nng opening of 3 fluoro-, 3,3-difluoro-, and 3-tnfluoromethylcyclobutene are consistent with the theoretical predictions of the effect of fluorine on this reaction [142] Surprisingly, fluonnated analogues of hexa tnene-cyclohexadiene systems undergo complex rearrangements mainly via free radical mechanisms and not by electrocyclic ring opening as expected [143] (equation 35)... 

Hydrolysis is probably a more complex process, since 3,4-bis(trifluoro-methyl)perfluorohexa-2,4-diene gives a cyclic product—perfluorotetra-methylfuran 46 (94JCS(P1)3119, 90JCS(CC)1127). The reaction involves vinyl substitution of fluorine with subsequent fast electrocyclization of the intermediate carbanion accompanied by fluoride ion elimination. An analogous reaction of 3,4-bis(trifluoromethyl)perfluorohexa-2,4-diene with sodium sulfide or thiourea forms perfluorotetramethylthiophene 47 (90JCS(CC)1127). 

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