Benzene, fluorobenzene, and p-difluorobenzene have been fluorinated in the vapour phase with a potassium cobaltifluoride complex to yield a number of known and new fluorocyctohexenes which have been fully characterised.THE fluorination of hydrocarbons in the vapour phase by transition-metal fluorides is well kn0wn.l Cobaltic fluoride has been used most frequently to give products which are mixtures of saturated fluoro-or fluorohydrocarbons, and in most cases olefins occur only as minor constituents. The present investigation stems from our earlier work 132 on cobaltic fluoride and is concerned with the use of a complex cobaltifluoride as the fluorinating agent. There are few reports of the use of complex metal fluorides for this purpose, and a potassium cobaltifluoride complex was chosen initially to compare its fluorinating ability with that of the parent cobaltic fluoride. The reagent was prepared by treatment of potassium trifluorocobaltate with elemental fluorine in a conventional stirred-bed apparatus.l The structure of the reagent is being investigated; it is probably potassium tetrafluor~cobaltate.~ Benzene was fluorinated as previously described for cobaltic fluoride.2 After each fluorination of hydrocarbon the reagent was regenerated by treatment with elemental fluorine. The products from a number of runs were combined and partially separated by fractional distillation into six fractions as shown in the Table. B.p. Yield range (g.1 Composition 4 6 -8 6 160 Benzene + perfluorocyclohexane and -hexene 58-99 33 (1) 3-(11) 100-110 83 (11) + (111) 4 (IV) 110-120 33 (IV) + (V) 140-175 95 (V) + ( V I ) + (VII) 120-126 171 (V) + (VI) yields (approx.). Compound (I) (8%), (11) (Syo), (Iv) (12%), (v) (35%)J (vl) (5%)J and (vll) (Oq5%)Each fraction was then separated into its components by preparative gas chromatography.

In exploring further the structural features that influence the relative efficacy of analogues of aminoglutethimide [1, 3-(4-aminophenyl)-3-ethylpiperidine-2,6-dione] as inhibitors of the cholesterol side-chain cleavage enzyme system desmolase and the estrogen forming system aromatase, analogues have been synthesized in which the aminophenyl substituent is replaced by pyridyl or substituted pyridyl. The 4-pyridyl analogue 5 [3-ethyl-3-(4-pyridyl)-piperidine-2,6-dione] is a strong competitive inhibitor of aromatase (Ki = 1.1 microM; value for 1, 0.60 microM), which exhibits a type II difference spectrum (Ks = 0.28 microM; value for 1, 0.13 microM) but is noninhibitory toward desmolase. The 2- and 3-pyridyl analogues (3 and 4) inhibit neither enzyme system. 1-Amino-3-ethyl-3-phenylpiperidine-2,6-dione (2) is a strong and selective inhibitor of desmolase but the 4-pyridyl analogue 10 [1-amino-3-ethyl-3-(4-pyridyl)-piperidine-2,6-dione] is a weak inhibitor of desmolase and aromatase. Analogues of 5 having a less basic aromatic substituent, namely, the N-oxide 11 and the 2,3,5,6-tetrafluoro derivative 13, were also prepared. The latter is a weak inhibitor of aromatase and the former inhibits neither enzyme system.

Pentafluorobenzaldehyde has been converted into a range of derivatives by reactions involving the carbonyl group, viz., a pentafluorostilbene, a pentafluorocinnamic acid, an azine, an oxime, and a range of acetals. Other derivatives were made by reactions involving replacement of fluorine using dimethylamine, sodium hydrogen sulphide, sodium thiophenoxide, and sodium methoxide.

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