Cyclohexanes 1,2-difluoro

TETROXIDO de NITOGENO (Spanish) (10544-72-6) Noncombustible, but supports combustion of combustible materials. A powerful oxidizer. Water contact produces nitric acid and nitric oxide. Incompatible with nitric oxide reacts with air, producing additional nitrogen tetroxide. Violent reaction with strong reducing agents, anhydrous ammonia, alcohols, barium oxide, boron trichloride, carbon disulfide, chlorinated hydrocarbons, cyclohexane, difluoro-trifluoromethylphosphine, dimethyl sulfoxide, formaldehyde, ethers, fluorine, formaldehyde, halocarbons, hydrocarbons, metal acetylides, metal carbides, metal powders, metal carbonyls. 

At room temperature the two chair forms average and the average symmetry is that of a planar molecule (C2v) 83) in which the fluorine atoms are related by the C2 axis and hence equivalent. Thus the room temperature spectrum of 1,1-difluoro-cyclohexane displays a single (except for proton splitting) chemical shift for the two fluorine atoms, as shown in Fig. 46 84,85). In contrast, at —110 °C the spectrum shows the expected AB pattern for the diastereotopic fluorine atoms expected from the individual structures shown in Fig. 46. As the temperature is gradually raised, the two doublets broaden and merge into two peaks which on further... 

Optimization studies undertaken to influence the ratio of products, including temperature, reagent stoichiometry, and solvents were unsuccessful. It was decided that for early evaluation of maraviroc the use of DAST was acceptable. Within the discovery setting, the inseparable mixture of the difluoro and vinyl fluoro cyclohexyl esters 20 and 21 was subjected to Upjohn conditions for dihydroxylation of vinyl fluoro side product 21. After an overnight reaction, the required difluorocyclohexyl ester 20 could be isolated in high purity by flash column chromatography. Saponification gave the acid 11, which could be recrystallized from cyclohexane to furnish analytically pure material. 

The photodecompositions of 3,3-bis(l,l-difluorohexyl)diazirine and 3-(l,l-difluoro-octyl)-3//-diazirine have been examined. On irradiation in cyclohexane or methanol, competing photoisomerization to linear diazo-compounds and photofragmentation via carbene intermediates to cyclopropanes and alkenes has been observed and is illustrated for 3,3-bis(l,l-difluorohexyl)diazirine (6) in Scheme 1. The majority of investigations of nitrogen photoelimination in cyclic... 

Conformational Analysis. - Freitas et al studied the conformational equilibrium of tra 5-l,2-difluoro-, tra s -l,2-dichloro-, and trani-l,2-dibromo-cyclohexanes, in which the halogen atoms have the two possible conformations of the axial-axial (aa) conformer and the equatorial-equatorial (ee) conformer. The observed /(H, H) coupling constant, is obtained as the weighted average of the aa conformer s coupling and the ee conformer s coupling Jee as follows ... 

Reactions of replacement of SMe [79], trichloromethyl [97] or trifluoromethyl groups represent effective approaches for modifications of trifluoromethyl containing 1,3,5-triazines. Direct vapor-phase fluorination of tris-(trifluoromethyl)-s-triazine 74 has been studied and was found that the perfluoroalkyl groups of 74 were progressively replaced by fluorine to give mixture of 2,4-difluoro-6-trifluoromethyl-s-triazine 156 and 2,4-bis-(trifluoromethyl)-6-fluoro-s-triazine 157 (Scheme 66) [98]. Photoirradiation of tris-(trifluoromethyl)-i-triazine in cyclohexane leads to a mixture of adduct 158 and dihydrocompound 159 (Scheme 66) [99]. 

A solution containing 2,2-difluoro-l,3-benzodioxole (5.7 mL, 7.9 g, 50 mmol) and sec-butyllithium (50 mmol) in tetrahydrofuran (65 mL) and cyclohexane (35 mL) is kept 2 h at -75 °C before fluorodimethoxyborane-diethyl etherate (9.4 mL, 8.2 g, 50 mmol instantly prepared by mixing the stoichiometrically required amounts of trimethylborate, boron trifluoride-diethyl etherate, and diethyl ether) and, at +25 °C, a 30% aqueous... 

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