Reactions involving fluoride ion Part XIII. Reactions of perfluoro-4-vinylpyridine

1-Chloro-1-(2′,3′,5′,6′-tetrafluoropyridyl)tetrafluoroethane, obtained by reaction of chlorotrifluoroethylene with pentafluoropyridine in the presence of caesium fluoride, was dehalogenated over iron at 310°, giving perfluoro-4-vinylpyridine (IV). Reactions of (IV) have been surveyed; nucleophilic attack occurs at both the ring and the difluoromethylene group using MeO^- but with PhO^-, selective attack at the difluoromethylene group occurred. A dimer is produced by reaction of (IV) with CsF and the intermediate carbanion was trapped with tetrafluoropyridazine. Thermal cyclodimerisation of (IV) gave a single isomer whose structure was established by n.m.r. and by defluorination to a cyclobutene. Cyclobutanes were formed in thermal cycloaddition reactions with chlorotrifluoroethylene and with hexafluoropropene. Photochemical reaction of (IV) with hexafluoroacetone gave an oxetane.     

Reactions involving fluoride ion. Part 21 [1]. Nucleophilic substitution reactions of perfluorocyclobutene oligomers

Reaction of perfluorocyclobutene oligomers, (1) - (4), with some simple nucleophiles gives products arising from S_N2′ displacement [N.B. this term is used here to describe the overall process of addition of a nucleophile to an alkene and elimination of an allylic fluorine and is not meant to imply that the reaction is concerted] or vinylic substitution of fluorine, or a mixture of both processes. The reactivity of the dimers, (1) and (2), is much greater than that of acyclic analogues and this can be attributed to the ring strain present in these compounds.     

Reactions involving fluoride ion. Part 34. A novel ring contraction

The CsF-catalysed isomerisation of perfluoro-1,1′-bis-1,3-diaza- cyclobex-2-enyl (1) in the absence of solvent gave perfluoro-4-methyl- 1,2,5,7-tetraazatricyclo[3.3.1.O^2.6]undec-4-ene (2) via intramolecular 1,3-attack at a saturated position in an intermediate nitrogen anion.     

Reactions involving fluoride ion. Part XII. Reactions of polyfluoro-aromatic compounds with octafluorobut-2-ene

Octafluorobut-2-ene is much more difficult to dimerise, with fluoride ion, than is hexafluoropropene but perfluoro-3,4-dimethylhex-3-ene is obtained under more forcing conditions. In contrast, polyfluoroalkylations with octafluorobut-2-ene are very efficient and results with perfluoro-pyridine, -pyridazine, and -quinoline are described, giving various perfluoro-2-butyl derivatives. Reactions with nitropentafluorobenzene and perfluorotoluene are also described. The ¹⁹F n.m.r. spectra of perfluoro-2-butylaromatic compounds reveal restricted rotation, even at room temperature.     

Reactions involving fluoride ion. Part 24 [1]. Syntheses from perfluorocyclobutene

Passage of perfluorocyclobutene, in a flow system, over caesium fluoride at 590–600^o provides a synthesis of hexa- fluoro-2-butyne in high yield. In a similar process, using glass tubes, tricyclo[3.3.0.0^2,6]octane and bicyclo[2.2.1] -2-heptene were obtained.     

Ion-selective electrodes in titrations involving azo-coupling reactions: Part 4. Determination of Secondary Amines

The determination of secondary amines (1–10 mg) is based on their reaction with arenediazonium ions to form triazenes. The sample is mixed with 4-bromo-1-naphthalenediazonium chloride and, when the coupling reaction is complete, the excess of diazonium salt is back-titrated with sodium tetraphenylborate. The end-point is easily evaluated from the sigmoidal potentiometric titration curves recorded with a PVC membrane indicating electrode plasticized with 2,4-dinitrophenyl n-octyl ether. Diethylamine, diethanolamine, piperidine, N-ethylaniline and 1-(N-methyl)amino-9,10-anthraquinone were used as test compounds.     

Reactions involving fluoride ion. Part 33 [1]. Perfluoroaza-alkylation of fluorinated heteroaromatics with perfluoro-1-methyl-1,3-diazacyclopent-2-and -3-ene

The nitrogen anion (1), generated by reaction of fluoride ion with (2), can be trapped by fluorinated heteroaromatics. Reaction of (1) with pentafluoropyridine gives a mono-substituted product. Mono- and di-substituted products are obtained with tetrafluoro-pyridazine and -pyrimidine, and fluoride ion catalysed isomerisation is observed. The mechanistic consequences of this are discussed. Reaction of (1) with trifluoro-1,3,5- triazine gives a tri-substituted product.     

Reactions involvlng fluoride ion. Part 26 [1] Nitranions from perfluoroazacyclohex-ene and -diene derivatives

The anion generated by addition of CsF to perfluoroaza-cyclohexene is very stable in sulpholane. Reaction of CsF with perfluoro-4-isopropylazacyclohexa-1,4-diene gives a less-stable anion and its behaviour with temperature is described.     

Thiophosphoryl fluoride and phosphoryl fluoride as initiators for the polymerisation of tetrahydrofuran

Thiophosphoryl fluoride and phosphoryl fluoride have been found to initiate the polymerisation of tetrahydrofuran. The living polymer formed has a high molecular weight of the order of a million and the density is found to be between 0.98 - 1.02 g/cc. A cationic mechanism for the polymerisation has been proposed.     

Methanol as hydrogen-donor in homogeneously catalysed reactions

Methanol in the presence of a number of soluble complexes of Rh, Ru, Ir or Os will hydrogenate organic functional groups, especially ketones and activated olefins. Methyl formate is also formed.     

胺作为配体在钯催化偶联反应中应用

对近期我们研究小组及其它研究小组在利用胺作为钯催化偶联反应的配体研究进展进行了总结. 钯/胺作为催化体系主要应用的偶联反应包括: Suzuki-Miyaura交叉反应, Sonogashira交叉反应, Stille交叉反应, Hiyama交叉反应和Heck反应. 研究结果表明胺可以作为价廉和高效的配体促进钯催化交叉偶联反应.     

Nucleophilic fluorination reactions starting from aqueous fluoride ion solutions

The sulfonium borane 2(+) reacts with fluoride anions in MeOH/H(2)O mixtures to afford the zwitterionic fluoroborate 2-F as an easily isolable nonhygroscopic solid. In dry acetonitrile, 2-F reacts with PhS(-) to afford the anionic fluoroborate 1-F(-). The latter is very labile and acts as a nucleophilic fluorination reagent toward a variety of substrates including alkylhalides and electron-deficient aromatic compounds. This approach may become broadly applicable to nucleophilic fluorination procedures that involve wet fluoride sources.     

New route to hybrid materials: Rhodium complex and fluoride ion catalysed hydrolysis of hydrogenosilanes

An alternative route to organosilsesquioxanes by hydrolytic condensation of the Si-H bonds of trihydrosilanes is described. This method avoids the formation of alcohols or acids since the leaving group is removed as hydrogen gas. The influence of the catalyst, ClRh(PPh₃)₃ or fluoride anion, on the properties of the resulting materials is discussed.     

Peroxo salts as initiators of vinyl polymerization. IV. Polymerization of methacrylamide initiated by peroxodisulfate ion and metal ion catalysis

The polymerization kinetics of methacrylamide (M) initiated by S₂O ion in the presence and absence of the metal ions Ag⁺ and Cu²⁺ has been studied. The rate laws have been established and are compared with those of acrylamide. The results indicate that steric hindrance from the α-methyl group affects the initiation reaction. Cu²⁺ ions are found to reduce the rate of polymerization.     

Ring-opening oligomerization reactions using aluminium complexes of schiff's bases as initiators

Bifunctional telechelics with defined structure can be prepared by oligomerization of oxiranes, β-butyrolactone and L-lactide using aluminium Schiff's base complexes as initiators. Chiral initiator (SALCENAlCl) shows a stereoelective character leading to preferential oligomerization of one enantiomer from a racemic monomer mixture. The reaction with β-butyrolactone proceeds through O-alkyl cleavage. Alkoxy Schiff's bases aluminium complexes are used for oligomerization of L-lactide. All the prepared oligomers were fully characterized by IR, elemental analysis, ¹H and ¹³C NMR and GPC.     

Ring closure reactions involving 1-hydrazinophthalazine. Reactions with 1,2,4-tricarbonyl and 1,3-dicarbonyl compounds

Annelation reactions of six-membered rings to 1-hydrazinophthalazine, 1, were investigated. With aroyl-(acyl)pyruvates, 2, the desired system was obtained. It was found that the course of the reaction depends on the reaction condition as well as the substituted pyruvates. Thus, 3-(2-oxo-2-substituted ethyl)-4H-as-triazino-[3,4-a]phthalazin-4-one, 4, was the product when 1 reacted with 2 in alcoholic medium. The side chain tauto-merism of 4 was studied by using ir, ¹H-nmr, and ms spectral methods. When 1 hydrochloride instead of 1 was reacted with 2, 3-ethoxycarbonyl-s-triazolo[3,4-a]phthalazine, 6, was the major product. The reaction of 1 with benzoylacetone in ethanol afforded the hydrazalone, 9. By ir, ¹H-nmr, and ¹³C-nmr methods it was shown that in solution it is inolved in an enhydrazine-hydrazone as well as a ring-chain tautomerism. Compound 9 upon the action of PPA underwent dehydrative cyclization to 3-methyl-s-triazolo[3,4-a]phthalazine, 10, and 3-methyl-5-phenyl-1-(l-phthalazinyl)pyrazole, 7. The reaction of 1 with ethyl phenylpropiolate in ethanol was reported by others to give 1-(1-phthalazinyl)-3-phenyl-5-pyrazolone, 8. Upon reinvestigation of this reaction it is shown that the product actually is ethyl β-(1-phthalazinylhydrazono)benzenepropanoate, 11. Attempts to synthesize 8 were unsuccessful by this method. In the reaction of 1 with ethyl benzoylacetate the expected hydralazone 11 was easily formed which upon reaction with PPA yielded the desired species 8.     

Pd-H from Pd/C and triethylamine: Implications in palladium catalysed reactions involving amines

The palladium hydride-iminium complex generated from Pd/C and triethylamine catalyses the isomerisation of allylic alcohols into carbonyl compounds, and Pd/C catalyses the conjugate reduction of activated double bonds using triethylamine as the source of the two newly incorporated hydrogen atoms via the same complex.     

The fluoride ion effect in the reactions of singlet oxygen with enols

The fluoride ion effect in the reactions of enolic systems with singlet oxygen has been investigated. β-Dicarbonyl compounds yielded 1,2,3-tricarbonyl derivatives, some of which underwent further hydration, whereas α-diketones suffered oxidative decarboxylation to give open-chain aldehydo-acids or keto-acids.