Methylations 1,10-phenanthroline, 1-oxide

Methylated phenanthroline is commonly oxidized to the aldehyde by selenium dioxide in dioxane, and then to the carboxylic acid by treatment with nitric acid.37,47 A selenium-free route to the aldehyde has been reported using iodine in DMSO.48... 

Although as noted above that monovalent copper complexes are sensitive to O2 and their reactions with O2 are fast, some Cu(I) complexes are stable in the presence of O2 (36,97,98). Thus [CuL ]+ does not react with O2 (27), and [Cu(I)fumarate] reacts only via dissociation to Cu (aq) as noted above (35). Another ligand which inhibits the reaction with O2 is 2,9-methyl-phenanthroline (89) (F i/2(oxidation) = 0.67 V in CH2CI2). All these ligands shift the redox potential of the Cu(II/I) couple anodically, thus decreasing the stability of the LCUO2 complexes and/or sterically inhibiting their formation. 

The NO reduction of the Cu(II) complex Cu(dmp)2(H20)2+ (dmp = 2,9-dimethyl-l,10-phenanthroline) to give Cu(dmp)2 plus nitrite ion (Eq. (20)) has been studied in aqueous solution and various mixed solvents (42a). The reduction potential for Cu(dmp)2(H20)2+ (0.58 V vs. NHE in water) (48) is substantially more positive than those for most cupric complexes owing to steric repulsion between the 2,9-methyl substituents that provide a bias toward the tetrahedral coordination of Cu(I). The less crowded bis(l,10-phenanthroline) complex Cu(phen)2(H20)2+ is a weaker oxidant (0.18 V) (48). 

A study of the regioselectivity of the 1,3-dipolar cycloaddition of aliphatic nitrile oxides with cinnamic acid esters has been published. AMI MO studies on the gas-phase 1,3-dipolar cycloaddition of 1,2,4-triazepine and formonitrile oxide show that the mechanism leading to the most stable adduct is concerted. An ab initio study of the regiochemistry of 1,3-dipolar cycloadditions of diazomethane and formonitrile oxide with ethene, propene, and methyl vinyl ether has been presented. The 1,3-dipolar cycloaddition of mesitonitrile oxide with 4,7-phenanthroline yields both mono-and bis-adducts. Alkynyl(phenyl)iodonium triflates undergo 2 - - 3-cycloaddition with ethyl diazoacetate, Ai-f-butyl-a-phenyl nitrone and f-butyl nitrile oxide to produce substituted pyrroles, dihydroisoxazoles, and isoxazoles respectively." 2/3-Vinyl-franwoctahydro-l,3-benzoxazine (43) undergoes 1,3-dipolar cycloaddition with nitrile oxides with high diastereoselectivity (90% de) (Scheme IS)." " ... 

For mixtures of the two oxidation states, the contact shifts depend directly on the relative mole fractions of the two states, indicating that the system is in the limit of rapid exchange. From this and the concentrations of the two species, one can calculate that the second-order rate constant involving the electron transfer must be greater than 106 M l seer1 at 25°C. This limit applies not only to the phenanthroline iron(II)—(III) system but also the iron(II)—(III) complexes with the following methyl derivatives of phenanthroline ... 

Improvements in the double Skraup synthesis of 1,7-phenanthroline from m-phenylenediamine now enable a yield of 70% to be achieved.163 The Skraup reaction continues to be used for the synthesis of 1,7-phen-anthrolines starting from the substituted 5-aminoquinolines. S-Chloro-6-hydroxy-1,7-phenanthroline (18) has been prepared in this way,164 and an improved synthesis of 6-hydroxy-1,7-phenanthroline was reported.165 As expected, the Skraup reaction on 5-aminoquinaldine affords 8-methyl-1,7-phenanthroline,166 not 2-methyl-1,7-phenanthroline as it was previously named.8 The extension of the Skraup reaction using methyl vinyl ketone instead of glycerol has been applied to 5-aminoquinoline to afford 4-methyl-1,7-phenanthroline.166 A related condensation using 2-hydroxymethylenecyclohexanone provides a route to benzo-substituted 1,7-phenanthrolines.167 7-Aminoquinoline with mesityl oxide in the presence of iodine gives 8,8,10-trimethyl-7,8-dihydro-l,7-phenanthroline (19).168... 

Reactions of 4,7-phenanthroline-5,6-dione have been the subject of considerable study. It is reduced to 5,6-dihydroxy-4,7-phenanthroline by Raney nickel hydrogenation226,249 or by aromatic thiols in benzene,262 and oxidized by permanganate to 3,3 -bipyridyl-2,2 -dicarboxylic acid.263 It forms bishemiketals with alcohols226 and diepoxides with diazomethane.226 The diepoxides by reaction with hydrochloric acid form diols of type 57, R = Cl, which on oxidation with lead tetraacetate give 3,3 -bipyridyl diketones of type 58, R = Cl. Methyl ketones of type 58, R = H, are also obtained by lead(IV) acetate oxidation of the diol 57, R = H, obtained by lithium aluminum hydride reduction of 57, R = Cl. With phenyldiazomethane and diphenyldiazomethane the dione forms 1,3-dioxole derivatives,264,265 which readily hydrolyze back to the dione with concomitant formation of benzaldehyde and benzophenone, respectively. 

NMO NMP Nu PPA PCC PDC phen Phth PPE PPTS Red-Al SEM Sia2BH TAS TBAF TBDMS TBDMS-C1 TBHP TCE TCNE TES Tf TFA TFAA THF THP TIPBS-C1 TIPS-C1 TMEDA TMS TMS-C1 TMS-CN Tol TosMIC TPP Tr Ts TTFA TTN N-methylmorpholine N-oxide jV-methyl-2-pyrrolidone nucleophile polyphosphoric acid pyridinium chlorochromate pyridinium dichromate 1,10-phenanthroline phthaloyl polyphosphate ester pyridinium p-toluenesulfonate sodium bis(methoxyethoxy)aluminum dihydride (3-trimethylsilylethoxy methyl disiamylborane tris(diethylamino)sulfonium tetra-n-butylammonium fluoride f-butyldimethylsilyl f-butyldimethylsilyl chloride f-butyl hydroperoxide 2,2,2-trichloroethanol tetracyanoethylene triethylsilyl triflyl (trifluoromethanesulfonyl) trifluoroacetic acid trifluoroacetic anhydride tetrahydrofuran tetrahydropyranyl 2,4,6-triisopropylbenzenesulfonyl chloride 1,3-dichloro-1,1,3,3-tetraisopropyldisiloxane tetramethylethylenediamine [ 1,2-bis(dimethylamino)ethane] trimethylsilyl trimethylsilyl chloride trimethylsilyl cyanide tolyl tosylmethyl isocyanide meso-tetraphenylporphyrin trityl (triphenylmethyl) tosyl (p-toluenesulfonyl) thallium trifluoroacetate thallium(III) nitrate... 

Its oxidized form (Phen)3Fe3+ is pale blue, while the reduced form (phen)3Fe2+ is red. The transition potential is about 1.11 V. Among the substituted derivatives of phenanthrolines, 5-methyl- and 5-nitro-1,10-phenanthroline complexes of iron have found wide applications in redox titrations. 

Charton (J52) has also applied the extended Hammett equation to the oxidation-reduction potentials of 5-substituted phenanthroline complexes of iron in various acidic media (95, 97, 651) and of bis-5- and 4,7-substituted phenanthroline complexes of copper in 50% dioxane (404). Thus, one should expect an overall similarity between the variations in pAa, stability constant, and oxidation-reduction potential data for the various ligands. The variations in a and )3 values found for various substitution positions and the tautomerism in the LH+ ions show that the correlation need not be good. A similar point may also be made about the comparison of data for the transoid bipyridylium ions and their cis complexes. Plots of A versus pA for various systems (95, 404) show a linear dependence to differing extents. As would be expected, the data for analogous complexes of iron (28), ruthenium (214, 217, 531), and osmium (111, 218, 220) show very good correlation. The assumption (152) that the effects of substituents are additive is borne out by these potential data, where the changes in potential on methyl substitution are additive (97). 

Cuprous chloride CuCl (mp 430 °C), when complexed with amines such as pyridine or phenanthroline, catalyzes the oxidation of alcohols to aldehydes and ketones by air [347]. In the presence of palladium dichloride, l dCl2, in aqueous dimethylformamide, terminal alkenes are converted by oxygen into methyl ketones [348],... 

Two examples of low temperature, catalytic, methane oxidation by hydrogen peroxide should be included in this section. The first involves conversion to methanol using cis-[Ru(2,9-dimethyl-l,10-phenanthroline)(solvent)2](PF6)2 as the catalyst [39]. A ruthenium-oxo species has been proposed as the C-H activating species. In the second report, conversion of methane to methyl hydroperoxide is claimed [40]. The catalyst is a combination of [NBuJ V03 and pyrazine-2-carbox-ylic acid. While the mechanism is uncertain, the actual oxidant is believed to be dioxygen with HO derived from hydrogen peroxide acting as the initiator. 

Phenanthroline-l-oxide loses the /7-oxide function on brief treatment with the carbanion derived from dimethylsulphoxide and sodium hydride to give benzo[h]quinoline in 48% yield. Prolonged reaction results in methylation of the benzoquinoline at the 5-and the 6-position (Y. Hamada et al, Chem. pharm. Bull. Japan, 1979, 1535). 

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