Tetroxide Bi

Another series of publications from Ken s group compared kinetic isotope effects, computed for different possible transition structures for a variety of reactions, with the experimental values, either obtained from the literature or measured by Singleton s group at Texas A M. These comparisons established the most important features of the transition states for several classic organic reactions — Diels-Alder cycloadditions, Cope and Claisen rearrangements, peracid epoxidations, carbene and triazolinedione cycloadditions and, most recently, osmium tetroxide bis-hydroxylations. Due to Ken s research, the three-dimensional structures of many transition states have become nearly as well-understood as the structures of stable molecules. 

Osmium tetroxide-Bis(3-methyl-2,4-pentanedionato)nickel(ll), 0s04/Ni(mac)2. 

Bismuth tetroxide Bi,04 12048-60-9 481.969 red-oran powder 306 6.6 reac EIjO... 

A few special syntheses of thiirane derivatives from four-membered sulfur heterocycles are known. Methylenethiiranes are derived by thermolysis of the tosylhydrazones of thietan-3-ones (Scheme 143) (81TL4815), and 2,2,3,3-tetrakis(trifluoromethyl)thiirane is obtained by thermolysis of 2,2,4,4-tetrakis(trifluoromethyl)-l,3-dithietane 1,1-dioxide with loss of sulfur dioxide. 2,2,3,3-Tetrakis(trifluoromethyl)thiirane 1,1-dioxide is obtained in low yield by heating a mixture of 3,3-bis(trifluoromethyl)-l,2,4-oxadithietane 2,2,4,4-tetroxide and bis(trifluoromethyl)ketene. The mono-episulfide of norbornadiene is obtained from thietane derivative (65 Scheme 144) (73JOC649). 

Many of the reactions already discussed for the preparation of bis-oxygenated pregnanes can also be used for the synthesis of 17,20,21-tris-oxygenated pregnanes by proper choice of substrate. Thus, reaction of a 17-vinyl-17-hydroxy steroid or a A -21-hydroxypregnene with osmium tetroxide will give the 17,20,21-triol, and the Stork reaction can be applied to 17a-hydroxy-20-keto steroids. 

Hydroxycortisone BMD) (48) A solution of 4 g of 17a,20 20,21-bis-methylenedioxypregn-4-ene-3,l 1-dione (cortisone BMD) (46) dissolved in 300 ml of t-butanol and 5 ml of water is treated with 34 ml of 35 % hydrogen peroxide and 0.45 g of osmium tetroxide predissolved in 36 ml of /-butanol. The resulting mixture is allowed to stand at room temperature for 2 days. Diol (47) which crystallizes during the reaction is collected by filtration and washed with /-butanol and water. The filtrate is diluted with ethyl acetate and washed sequentially with aqueous sodium chloride, aqueous 10% sodium bisulfite, aqueous 10% sodium bicarbonate and finally with water to neutrality. The solvent is evaporated and a second crop of the diol (47) is collected, providing a total of about 3.8 g. 

The 1,3-dithietane tetroxides (7b) readily undergo tetra-a-halogenation275 with either Br2 or Cl2, but not with I2. Partial a-halogenation in this series can be accomplished indirectly by starting from either 2,4-bis(trimethylsilyl)- or 2,4-bis(t-butyldimethyl-silyl)-l, 3-dithietane tetroxides (275) as shown in equation 103275. In all of the above reactions one takes advantage of the highly acidic a-hydrogens and, consequently, the... 

To the best of the author s knowledge, the only isolated diaza analog of o-benzoquinone is bis-N-oxide 79 and its derivatives. Compound 79 was isolated as orange-colored crystals from a reaction of tetraketo derivative 78 with dinitrogen tetroxide (76TL1703 77AP264). 

The reactions of diazoesters with hydrochloric and sulfuric acids, triphenylphosphine, and dinitrogen tetroxide resulted in aryl chloroacetates, bis(aryloxycarbonylmethyl) sulfates, triphenylphosphoranylidenehydrazones of aryl 2-oxoethanoates, and iV-oxides of diaryl l,2,5-oxadiazole-3,4-dicarboxylates <1999RJO 666>. 

The equilibrium between 1,1-dimethylethylperoxyl radicals and 1,1-dimethylethyl tetroxide was first evidenced by Bartlett and Guaraldi [157] for peroxyl radicals generated by irradiation of bis( 1,1-dimethylethyl) peroxycarbonate in CH2C12 at 77 K and oxidation of 1,1-dimethylethyl hydroperoxide with lead tetraacetate at 183 K in CH2C12. A series of studies of this equilibrium were performed later using the EPR technique (see Table 2.12). It is seen that the enthalpy of tetroxide decomposition ranges from 29 to 47 kJ mol-1. 

Carbocations as electron acceptors in aromatic EDA complexes 192 Bis(arene)iron(II) complexes with arene and ferrocene donors 198 Carbonylmetallate anions as electron donors in charge-transfer salts 204 Aromatic EDA complexes with osmium tetroxide 219... 

The 1,4,2,3-dithiadiazepine tetroxide (617) is simply prepared by the reaction of the bis-sulfonyl chloride C102S(CH2)3S02C1 with hydrazine hydrate (73CB713) and the benzo fused 1,3,4,7 system (618) is produced by reacting o-phenylenediamine with bis(chloro-sulfonyl)methane (CIO2SCH2SO2CI) (77JHC493). 

The equilibrium between 1,1-dimethylethylperoxyl radicals and 1,1-dimethylethyl tetroxide was first evidenced by Bartlett and Guaraldi [157] for peroxyl radicals generated by irradiation of bis( 1,1-dimethylethyl) peroxycarbonate in CH2C12 at 77 and oxidation of... 

LACTONES Bis(3-dimethylaminopro-pyDphenylphosphine. Copper(I) tri-fluoromethanesulfonate. Di-n-butyltin oxide. Dichlorobis(triphenyl-phosphine)-palladium. Ruthenium tetroxide. a-LACTONES lodosobenzene. 

Using chromium-based oxidants 2,4-Dimethylpentane-2,4-diol chromate(VI) diester, 122 Trimethylsilyl chlorochromate, 327 Using other oxidizing agents Bis(tributyltin) oxide, 41 Hydrogen hexachloroplatinate(IV)-Copper(II) chloride, 145 4-Methoxy-2,2,6,6-tetramethyl-1 -oxopiperidinium chloride, 183 Osmium tetroxide, 222 Potassium nitrosodisulfonate, 258 Samarium(II) iodide, 270 From alkenes by addition or cleavage reactions... 

Trimethylsilyldiazomethane, 327 Silyl substituted arenes Bis(trimethylsilyl)acetylene, 97 Chromium carbene complexes, 82 Titanium(IV) chloride-Diethylalu-minum chloride, 309 Other organosilanes Osmium tetroxide-Trimethylamine N-oxide-Pyridine, 223 Tributyltin chloride, 315 Di- x-carbonylhexacarbonyldicobalt, 99 Trimethylsilyl trifluoromethanesul-fonate, 329... 

Osmium tetroxide-N-Methyl-morpholine N-oxide, 222 Osmium tetroxide-Trimethylamine N-oxide-Pyridine, 223 Palladium Compounds Benzylchlorobis(triphenylphosphine)-palladium(II), 30 Bis (ace tonitrile) chloronitropalla-dium(II)-Copper(II) chloride, 33 Bis(acetonitrile)dichloropalladium(II), 33, 211, 236... 

Ruthenium(IV) oxide-Sodium periodate, 268 Ruthenium tetroxide, 268 Tetrachlorotris [ bis (1,4-diphenylphos-phine)butane]diruthenium, 288 Tetrakis(trifluoroacetate)ruthenium, 289... 

To improve the position selectivity in the AD of oligoprenyl compounds bis-cinchona alkaloid ligand 8 was introduced by Corey 15,6]. Its design was based on the [3+2]-cycloaddition model for the AD mechanism, which will be discussed in Section 6E. 1.2. The two 4-heptyl ether substituents of the quinolines are supposed to assist fixation of the substrate in the binding cleft. Additionally, the jV-methylquinuclidinium unit and the linking naphthopyridazine were introduced to rigidify the osmium tetroxide complex of 8 [6],... 

---