Steven J. Mullins

Fluorinated di-enes

Abstract Fluorinated di-enes may be obtained by the defluorination of some oligomers of F -alkenes and -cycloalkenes using tetrakis(dimethylamino)ethene. These di-enes are very susceptible to nucleophilic attack. Nucleophilic epoxidation of ( 4 ) gives a new diepoxide which undergoes a novel ring-opening reaction. Di-ene ( 4 ) forms cyclopentadienylide derivatives with di-functional carbon nucleophiles and a cyclopentadienylide salt ( 17 ) is obtained in a remarkable ‘one-pot’ reaction from hexachlorobutadiene.

Reactions involving fluoride ion. Part 39. Reactions of perfluorinated dienes with oxygen and sulphur nucleophiles

The order of reactivity of perfluorinated dienes towards methanol is 3 > 21 and the process is activated by release of angle strain. The diene 1 is hydrolysed to give perfluorotetramethyl-furan and the corresponding thiophene, is obtained by an analogous process using K2S. Hydrolysis of compounds 2 and 3 yields diketones that are strong acids. Reactions of phenols and thiophenols with 1 give aryl ethers and sulfides and difunctional nucleophiles react with 1 to give potential polymer precursors.

SYNTHESES OF PERFLUORINATED EPOXIDES, DIEPOXIDES, AND A NOVEL REARRANGEMENT

Abstractt-Butylhydroperoxide/butyl-lithium is a good reagent for synthesis of epoxides and diepoxides from polyfluorinated-alkenes and-polyenes. This reagent and calcium hypochlorite both give a novel diepoxide 5 from perfluoro-3,4-dimethyl-2,4-diene 1; diepoxide 5 undergoes a novel rearrangement, at 200°C, to the corresponding 1,4-dioxine derivative 18. Possible mechanisms are discussed.

A synthesis of novel perfluorodienes

Oligomers of perfluoroalkenes are converted to dienes in good yields, using sodium amalgam; these dienes are highly susceptible to nucleophilic attack and can be excellent sources of heterocycles.

Reactions involving fluoride ion. Part 42.1 Heterocyclic compounds from perfluoro-3,4-dimethylhexa-2,4-diene

Reactions of perfluoro-3,4-dimethylhexa-2,4-diene 1 with primary aromatic amines give both pyrrole 2 and pyrroloquinoline 3 derivatives, whilst ammonia gives dienes 10 and 12 as well as the novel pyrrole derivative 11. Catechol leads to a benzodioxocine system 18 and this can be epoxidised to a mixture of mono- 21 and di-epoxides 20. Electrocyclisation of 18 occurs with ultraviolet irradiation, giving 22.

Direct syntheses of pentakis(trifluoromethyl)cyclopentadienide salts and related dienes

Direct routes for the synthesis of pentakis(trifluoromethyl)cyclopentadienide salts, hexakis(trifluoromethyl)cyclopentadiene and 5H pentakis(trifluoromethyl)cyclopentadiene are described.

Reactions involving fluoride ion. Part 38. New fluorinated dienes by defluorination

The oligomers 2, 4 and 6, 6a, derived from tetrafluoroethene, octafluorocyclopentene, and hexafluorocyclobutene respectively, are converted into their corresponding dienes 7–9 by defluorination, using sodium amalgam. An alternative route using tetrakis(dimethylamino)ethene (TDAE) is also described and forms a fluoride salt of TDAE. The diene 7 shows a remarkably low extinction coefficient for UV absorption.

Stable fluorinated aryl- and cyclopentadienyl-anions

Abstract Aryl anions of type (1) are potentially useful probes to study the effect of fluorine substituents on charge distributed in an aromatic ring (1a), which is of obvious interest in relation to nucleophilic aromatic substitution. Consequently, we have synthesised a series of stable aryl anions of type Ar F -CXY and the spectra of these systems will be discussed. We will also describe a rational synthesis to a series of novel stable fluorinated cyclopentadienyl anions of general structure (3), via the dienes (2).

Charge-transfer salts containing cyclic perfluorinated anions

Abstract Perfluorobicyclopentenyl (1a) and -butenyl (2a) react with decamethylferrocene (3) , to give charge-transfer salts 4 and 5 , respectively; perfluorohexakis(trifluoromethyl)cyclo-pentadiene (6) forms a salt (8) containing the C 5 (CF 3 ) 5 anion. Crystal structures of the salts 4 and 5 have been determined; both contain centrosymmetric trans -diene radical anions.

An unusual rearrangement of a diepoxide

The diepoxide derived from perfluoro-3,4-dimethyl-2,4-diene undergoes quantitative rearrangement, at 200 °C, to the corresponding 1,4-dioxine derivative.