Chemical consequences of fluorine substitution. Part 4. Diels–Alder reactions of fluorinated p-benzoquinones with Dane's diene. Synthesis of fluorinated D-homosteroids

The trifluoromethoxy group as a fluorine twin in the Diels–Alder reactions of halogenated quinones

“…Usually DielsAlder reactions of common quinones occur exclusively via an endo transition state. 16 It has been reported, however, that some fluorinated dienophiles 8,17 gave sometimes the products arising from an exo transition state. 1 H NMR spectra run in CDCl 3 were useless for this purpose, very important signals from H1, H4, and H8a being highly crowded in a very narrow range (3.5-3.6 ppm).…”

“…In order to overcome the leveling effect resulting from the strong tendency of fluorobenzoquinone to give mainly addition products toward its hydrogenated side under kinetic conditions, 7,8 we selected to study the behavior of mixed 'halogenated' quinones (2-chloro-6-fluoro and 2-chloro-6-trifluoromethoxy benzoquinones) toughed to enable a finer analysis of the relative effects of these halogen atoms.…”

Synthesis and Diels–Alder reactions of α-fluoro- and α-trifluoromethylacrylonitriles

“…cyclohexene derivatives [40,41]. This type of reactions has been shown to be of particular interest in syntheses of fluorinated analogues of biologically active compounds such as cantharidin, endothall [42] and D-homosteroids [43]. Previously, we found that simple vinyl fluorides such as a-or b-fluorostyrenes are weak dienophiles which only react with very active dienes like diphenylisobenzofuran [44,45] or some fluorinated cyclohexa-2,4-dienones [46].…”

Novel Synthesis of Perfluoro1,4-benzoquinones by Anodic Oxidation

“…On the other hand, similar anodic oxidation of octafluoronaphthalene (3) brought about predominant formation of hexafluoro-1,4-naphthoquinone (4) 8) in a 52% yield under the similar conditions. Similar anodic oxidation of 1,2,4-trifluorobenzene (5), 1,2,3,4-tetrafluoro benzene (6), and 1,2,4,5-tetrafluorobenzene (7) under the same conditions brought about formation of 2-fluoro-(8) 9) , 2,3-difluoro-(9) 10) , and 2,5-difluorobenzo-1,4-quinones (10) 11) , respectively, in 35-18% yields, as shown in Table 2.…”