The preparation and properties of polyfluoro aromatic and heteroaromatic compounds

Polyfunctional Tetrahydropyrido[2,3-b]pyrazine Scaffolds from 4-Phenylsulfonyl Tetrafluoropyridine

[Reaction: see text]. Polyfunctional tetrahydropyrido[2,3-b]pyrazine scaffolds can be synthesized by sequential reaction of pentafluoropyridine with sodium phenylsulfinate and an appropriate diamine. The polyfunctionality possessed by the difluorinated tetrahydropyrido[2,3-b]pyrazine scaffolds was demonstrated in selected model reactions with nucleophiles to give access to various polysubstituted [6,6]-ring fused systems.

Tetrahydropyrido[3,4-b]pyrazine Scaffolds from Pentafluoropyridine

[reaction: see text] Representative polyfunctional tetrahydropyrido[3,4-b]pyrazine scaffolds have been synthesized very readily by a one-pot annelation reaction of pentafluoropyridine with appropriate diamines. The trifluorinated pyridopyrazine products react sequentially with various nucleophiles to give poly-substituted tetrahydropyridopyrazines, demonstrating the potential of the polyfluorinated ring fused pyridine system as a scaffold for the synthesis of previously inaccessible poly-substituted pyridopyrazine derivatives. This general approach has special relevance to the development of new chemical entities for the life science industries and particularly in the drug discovery arena, in which low molecular weight, polyfunctional heterocyclic derivatives are playing an increasingly important role.

Routes to fluorinated organic derivatives by nickel mediated C-F activation of heteroaromatics

New fluorinated azaheterocycles can be synthesised regio- and chemo-selectively via C-F activation of fluorinated precursors at nickel, with subsequent functionalisation and release from the coordination sphere of the metal; the requirements for productive C-F activation are significantly different from those for C-H bond activation.

Efficient, high-yield route to long, functionalized p-phenylene oligomers containing perfluorinated segments, and their cyclodimerizations by zirconocene coupling

Linear oligophenylene diynes containing 6, 9, and 12 phenylene rings were synthesized in high yields using the nucleophilic aromatic substitution (S(N)Ar) of perfluoroarenes by aryllithium reagents as the key carbon-carbon bond-forming reaction. This reaction was demonstrated to proceed readily at low temperatures with sterically hindered substrates and in the presence of base-sensitive silylalkynyl groups. Diynes synthesized by this methodology were readily zirconocene-coupled into large dimeric macrocycles using the zirconocene reagent Cp(2)Zr(py)(Me(3)SiC triple bond CSiMe(3)).

Trimethylsilyl- and trimethylstannyldimethylphosphane--convenient and versatile reagents for the synthesis of polyfluoroaryldimethylphosphanes

Trimethylsilyldimethylphosphane (Me3SiPMe2) and the corresponding tin compound (Me3SnPMe2) were used as reagents for the substitution of fluorine by the Me2P group in polyfluoroarenes C6F5X (X = F, H, Cl, CF3) and C5NF5. The reactions occur even under mild conditions (T = 0-20 C), either in benzene or without solvent, to give as a rule 4-X-1-(dimethylphosphano)tetrafluorobenzenes (XC6F4PMe2, 1-4) and 4-(dimethylphosphano)tetrafluoropyridine (C5NF4PMe2, 5), respectively, in yields between 75 and 95%. In the case of C6F6, double substitution is also observed, which affords 1,4-bis(dimethylphosphano)tetrafluorobenzene (6). A very efficient route to the compounds XC6F4PMe2 (X = F, H, Cl, CF3) and C5NF4PMe2 was developed as a one-pot reaction of the corresponding fluoroarenes with tetramethyldiphosphane (P2Me4) and trimethyltin hydride (Me3SnH) at moderate temperatures. This process was tested for C6F6 and perfluorobiphenyl which gave C6F5PMe2 (1) and 4,4'-bis(dimethylphosphano)octafluorobiphenyl (7), respectively. The results, which included kinetic measurements that used the intensities of the 31P signals, revealed the influence of the substrate type on the rate of reaction in the sequence: C5NF5>C6F5CF3> C6F5Cl, C6F5PMe2>C6F5H>C6F6>> C6H5F. Ab initio calculations were carried out on the model reactions of pentafluoropyridine with silylphosphane, phosphane or phosphide to discriminate between possible reaction mechanisms. The novel phosphanes were characterised by spectroscopic investigations (NMR, MS), by preparation of the related thiophosphanes ArFP(=S)Me2 (8-14), their spectroscopic and analytic data and single crystal X-ray diffraction studies on five of these derivatives.