Isoquinoline, perfluoro

Fluonnation of isoquinoline gave a mixture of partly and fully fluorinated compounds of which perfluoro-3,4,5,6,7,8-hexahydroisoqumoline and perfluoromethylcyclohexane were fully identified [28] (equation 11)... 

Fluorination. Attention has been focused on the direct fluorination of isoquinolines activated by conversion into 2-methylisocarbostyril (80). With gaseous fluorine (diluted to 10% with argon) in acetic acid a 54% yield of the 4-fluoro derivative was obtained. (Scheme 40). With methylene chloride as the solvent, only the 4-chloro analogue was formed [82H( 17)429]. Fluoroisoquinolines have also been made by displacement of nitro groups, and from diazonium fluoroborates (87JHC181). Hepta-chloroisoquinoline was converted into a perfluoro derivative by heating it in an autoclave with anhydrous potassium fluoride [66JCS(C)2328]. 

Isoquinoline over cesium tetrafluorocobaltate(III) reacts at 335-340°C to give98 a 40-50% yield of a mixture of at least 10 components the only ones identified being perfluoro(methyl-cyclohexane) and the bicyclodiene 17. 

New representatives of such polyimides were prepared from TNT-based perfluoro-substituted m-phenylenediamines and different aromatic tetracarboxylic acid dianhydrides [9-12] in accordance with Scheme 5.2. Reactions were carried out in w-cresol using isoquinoline as catalyst. The reaction temperature was 160 °C and the reaction time 5 hours. 

OCH3 and NH3, give exclusive attack at the hard electrophilic centres, i.e. C—F, whereas soft nucleophiles displace bromine. This is further evidence for the importance of ion-dipole interactions, regarding attack at C—F bonds. Reactions of perfluoro-quinoline and -isoquinoline with hard and soft nucleophiles have also revealed a sensitivity towards a change in orientation of attack with the nature of the nucleophile [114] (Figure 9.42). 

A number of reports concern the attack of nucleophiles on perfluoro-olefins to give cumulenes or heterocumulenes, which in turn imdergo nucleophilic attack to give heterocyclic compounds with perfluoroalkyi substituents. o-Phenylenedi-amine reacts with hexafluoropropene to give 2-(o j8j8>tetrafluoroethyl)benzimidazole (301) ketenimine intermediates have also been utilized in the formation of quinolines (302) (see p. lll) 89.59o j,y intramolecular cyclization, and (303) (see p. 112) by intermolecular cyclization, naphthyridines (304), pyridopyrimidines (305), and isoquinolines (306). The pyran derivative (307) is formed via isomerization of an allene intermediate (see p. 100). 3-Fluoro-2-isopropyl-l,2,4-thiadiazolin-... 

Exceptionally, there is an example for simultaneous construction of both benzene and pyridine rings toward a perfluorinated isoquinoline. Feast et al. reported the synthesis of perfluoro-3-methylisoquinoline via the hetero Diels-Alder reaction of perflu-oro-l,4,6,7-tetrahydro-l,4-ethanonaphthalene with trifluoroacetonitrile followed by pyrolysis, which involved elimination of tetrafluoroethylene (Scheme 25) [93]. 

Patents have been published which deal with nucleophilic substitution in tetrafluoro-4-nitropyridine (c/. ref. 264), the preparation and reactions of perfluoro-quinoline and -isoquinoline (cf. ref. 267), the preparation and nucleophilic substitution reactions of perfluoro-pyridazine (cf. ref. 269) and -pyrazine (cf. ref. 270), and the preparation of reactive dyestulfs containing fluoro-pyridazine or -pyrimidine residues via displacement of fluorine from polyfluoropyridazines or 5-chlorotrifluoropyrimidine, respectively, with amino- or phenoxy-compounds. The results of the work on perfluoropyrazine are summarized in Schemes 39 and 40. 

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