Thallium tetrafluoroborate

As illustrations. Tables 2 and 3 list assignments for the H-NMR spectra of two important bryostatins and two bryostatin acetates while Fig. 5 lists assignments for the C-NMR spectrum of bryostatin 12. Fig. 6 shows the ultraviolet spectra, while mention of other ultraviolet, infrared, and mass spectral characteristics has already been made in Section 5. However an illustration of the application of mass spectrometry to the structure elucidation of bryostatins 5-7 will be instructive (27). The solution phase secondary ion mass spectra of these three bryostatins were quite revealing when new techniques for detecting molecular ions of hitherto refractory substances were utilized. By employing an alkali metal iodide such as sodium iodide or silver tetrafluoro-borate or thallium tetrafluoroborate in sulfolane the molecular ions... 

McNeese and Mueller have shown35 that [VCKSchiff Base)] complexes lose halide in reactions with thallium tetrafluoroborate in acetone. The corresponding solvento-complexes are generated along with thallium chloride. The use of silver salts in such reactions could lead to oxidation of the starting material. 

Like thallium(I) fluoride (see Section 18.2.), silver(I) tetrafluoroborate is used to convert chloro-formates into the corresponding fluoroformates, which are decomposed to the fluorides as described in Section 16.1.2. Phenyl fluoroformate (4) is obtained in moderate yield in this way from 3.68... 

Glycosidation Allyl chloroformate, 9 Boron trifluoride etherate, 43 Silver(I) tetrafluoroborate, 273 Silver (I) trifluoromethanesulfonate, 274 Thallium zeolites, 296 Tin(II) trifluoromethanesulfonate, 301 Trichloroacetonitrile, 321 Grignard reactions and reactions of... 

The case of p-hydroxy-y-alkenyl selenides merits further comments. The rearrangement efficiently takes place using the thallium(I) ethoxide method and the presence of an additional double bond in the reactant does not introduce a serious problem associated with unwanted reaction with the dichlorocarbene intermediate. This is not the case when silver tetrafluoroborate is used. 

The action of n-butyllithium in THF at low temperature leads to the anion. After reaction with an electrophilic compound, e hydrolysis can generally be carried out in polar solvents (acetone, alcohols, acetonitrile) in the presence of mercury(II) chloride or oxide and water.In other cases, NBS, - chloramine T, cerium(IV) ammonium nitrate, n-tributyltin hydride, trialkyloxonium tetrafluorobor-ate, thallium nitrate or photochemistry can be used. Desulfurization by Raney nickel gives hydro-carbons. ... 

The electrophilic substitution is the most characteristic reaction for these classes of compounds. Compound (21) undergoes standard electrophilic aromatic substitution reactions. Thus it forms the 6-bromo compound (58) with A7-bromosuccinimide and 6,7-dibromo compound (72) with the excess of the same reagent. It also forms the 6-nitro compound (67) with copper(II) nitrate trihydrate and 6,7-dinitro compound (68) with excess of nitronium tetrafluoroborate. The bis(trifluoro-acetoxy)thallium derivative (73) was formed from trithiadiazepine (21) and thallium(III) trifluoro-acetate in refluxing acetonitrile. Without isolation, (73) was directly converted into the pale yellow 6-iodo compound (74) with aqueous potassium iodide, into the 6-cyano compound (75) with copper(I) cyanide, and into methyl trithiadiazepine-6-carboxylate (76) with carbon monoxide and methanol in the presence of palladium chloride, lithium chloride, and magnesium oxide. Compound (21) is acetylated in the presence of trifluoromethanesulfonic acid (Scheme 7) <85CC396,87JCS(P1)217, 91JCS(P1)2945>. 

OXIDATION, REAGENTS Acetyl nitrate. Bis(tri-n-butyltin)oxide. Bromine-Hexameth-ylphosphoric triamide. f-Butyl perbenzoate. Ceric ammonium nitrate. N-chlorosuc-cinimide-Dimethyl sulfide. Chromic add. Chromic anhydride. Chromic anhydride-Acetic anhydride. Chromic anhydride-Hexamethylphosphoric triamide. 2,3-Dichloro-5,6-dicyano-l,4-benzoquinone. Dimethyl sulfoxide. Dimethyl sulfoxide-Trifluoro-acetic anhydride. Diphenylseleninlc anhydride. Iodine tris(trifluoroacetate). Lead tetraacetate. N-Methylmorpholine -N-oxide. p-NitrobenzenesulfonyI peroxide. Oxygen, singlet. Palladlumfll) chloride. Peroxybcnzimidic acid. Phenylseleninyl chloride. N-Phenyl-l,2,4-triazoline-3,5-dione. Potassium chromate. Potassium superoxide. Pyri-dinium chlorodiromate. Salcomine. Silver carbonate-Celite. Sodium hypochlorite. Sulfuryl chloridc-Silica gel. Thallium(III) acetate. ThaUium(III) nitrate. Triphenyl phosphite ozonide. Trltyl tetrafluoroborate. Uranium hexafluoride. 

The coupling of electron-rich olefins in conventional solvents often requires additives such as silver triflate or thallium acetate to obtain high a/p selectivity. 1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIm]BF4) is an excellent catalytic system for highly regioselective a-arylation of several electron-rich olefins. Butyl vinyl ether 9 reacted with p-bromobenzaldehyde 10 selectively afp ratio >99 1) to 11 (Scheme 15.3 [42]). Comparative experiments in conventional solvents (e.g. DMF) resulted in product mixtures with aip ratios of 46 54 to 69 31. It has been suggested that the ionic pathway is responsible for the unique regiocontrol in the ionic liquid [48-50]. 

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