Nitration Dimers

Figure 12 The structure of the dimethyltin hydroxide nitrate dimer (Reproduced from J.C.S. Dalton, 1974, 475)...

Ttinitroparaffins can be prepared from 1,1-dinitroparaffins by electrolytic nitration, ie, electrolysis in aqueous caustic sodium nitrate solution (57). Secondary nitroparaffins dimerize on electrolytic oxidation (58) for example, 2-nitropropane yields 2,3-dimethyl-2,3-dinitrobutane, as well as some 2,2-dinitropropane. Addition of sodium nitrate to the anolyte favors formation of the former. The oxidation of salts of i7k-2-nitropropane with either cationic or anionic oxidants generally gives both 2,2-dinitropropane and acetone (59) with ammonium peroxysulfate, for example, these products are formed in 53 and 14% yields, respectively. Ozone oxidation of nitroso groups gives nitro compounds 2-nitroso-2-nitropropane [5275-46-7] (propylpseudonitrole), for example, yields 2,2-dinitropropane (60). 

A -Pyrazolines such as (410) are oxidized by iodine, mercury(II) acetate and trityl chloride to pyrazolium salts (411), and compound (410) even reduces silver nitrate to Ag° (69JOU1480). Electrochemical oxidation of l,3,5-triaryl-2-pyrazolines has been studied in detail (74BSF768, 79CHE115). They Undergo oxidative dimerization and subsequent transformation into the pyrazole derivative (412). 

Jap-KIingermarm reactions, 4, 301 oxidation, 4, 299 reactions, 4, 299 synthesis, 4, 362 tautomerism, 4, 38, 200 Indole, 5-amino-synthesis, 4, 341 Indole, C-amino-oxidation, 4, 299 tautomerism, 4, 298 Indole, 3-(2-aminobutyl)-as antidepressant, 4, 371 Indole, (2-aminoethyl)-synthesis, 4, 278 Indole, 3-(2-aminoethyl)-synthesis, 4, 337 Indole, aminomethyl-reactions, 4, 71 Indole, 4-aminomethyl-synthesis, 4, 150 Indole, (aminovinyl)-synthesis, 4, 286 Indole, 1-aroyl-oxidation, 4, 57 oxidative dimerization catalysis by Pd(II) salts, 4, 252 Indole, 1-aroyloxy-rearrangement, 4, 244 Indole, 2-aryl-nitration, 4, 211 nitrosation, 4, 210 synthesis, 4, 324 Indole, 3-(arylazo)-rearrangement, 4, 301 Indole, 3-(arylthio)-synthesis, 4, 368 Indole, 3-azophenyl-nitration, 4, 49 Indole, 1-benzenesulfonyl-by lithiation, 4, 238 Indole, 1-benzoyl photosensitized reactions with methyl acrylate, 4, 268 Indole, 3-benzoyl-l,2-dimethyl-reactions... 

We have noted above that benzocrowns may be nitrated quite readily. This approach was used in the formation of a photoresponsive bis-crown (see Sect. 3.8) wherein the nitrobenzo crowns reductively dimerize to the corresponding azobenzene. Kikukawa, Nagira and Matsuda have utilized 4-nitrobenzo-15-crown-5 in a somewhat different way during the synthesis of 4 -vinylbenzo-l 5-crown-5Nitration is effected using nitric acid in a mbcture of chloroform and acetic acid. 

Figure 11.19 Schematic diagram of the centrosymmetric dimer in [Cii2(NO ).i(py) lpy showing the two bridging nitrato groups each coordinated to the 2 Cii atoms by a single O atom the dimer also has an unsymmetrical bidentate nitrate group on each Cu.

It is not clear why some organisms have two 14-3-3 isoforms while others have up to 12. Binding 14-3-3 inhibits the plant enzyme nitrate reductase and there appears to be no selectivity between plant 14-3-3 isoforms in fact yeast and human isoforms appear to work equally as well in vitro. The best example where selectivity has been demonstrated is human 14-3-3o. 14-3-3o Preferential homodimerizes with itself and crystallization revealed a structural basis for this isoform s dimerization properties as well as for its specific selectivity for target binding proteins. Here partner specificity is the result of amino acid differences outside of the phosphopeptide-binding cleft. 

Chemical analyses reveal that measurable amounts of uranyl ion are actually present in Pu(IV) polymers grown in mixtures of Pu(IV) and uranyl nitrate suggesting that uranyl ion is being taken up in the polymer network and consequently hampers the growth through a chain termination process as suggested in Fig. 3. The uranyl serves to terminate active sites because it does not typically form extensive polymeric aggregates as does Pu(IV) instead it tends only to dimerize and, at most, tri-merize (4). 

Silyi enol ethers can be dimerized to symmetrical 1,4-diketones by treatment with Ag20 in DMSO or certain other polar aprotic solvents." The reaction has been performed with R , R = hydrogen or alkyl, though best yields are obtained when r = r = H. In certain cases, unsymmetrical 1,4-diketones have been prepared by using a mixture of two silyi enol ethers. Other reagents that have been used to achieve either symmetrical or cross-coupled products are iodosobenzene-Bp3-Et20," ceric ammonium nitrate," and lead tetraacetate." If R =0R (in which case the substrate is a ketene silyi acetal), dimerization with TiCU leads to a dialkyl succinate (34, r =0R)." ... 

Oxidation of aknadinine with silver nitrate gave a pair of dimeric compounds, one of which was identical to the naturally occurring bisaknadinine (8) and the other assumed to be a stereoisomer arising from an axial chirality concerning the mode of biphenyl linkage (21,22). It was impossible, however, to determine from ORD and CD measurements whether the isomer is of natural bisaknadinine (8). Therefore, unambiguous proof of the stereochemistry was achieved, using the X-ray diffraction method, and the... 

Siloxycyclopropane 2 is eluted very quickly. Final fractions contain dimethyl lumarate and maleate. If mixtures of 2 with these carbene dimers are obtained, the nitration through alumina has to be repeated. 

An oxidative radical coupling promoted by tetra-ra-butylammonium cerium(IV) nitrate (TB ACN) between P-aminocinnamate 22 and enamine 23 provided pyrrole-3,4-dicarboxylate 24 <06T2235>. Dimerization of the P-aminocinnamates provided symmetrical pyrroles. 

A variety of derivatives of bis-[Bi(tr)2X, X = Cl or N03], tris-(Bitr3), and tetra-([Bi(tr)4X][Na]) tropolonate complexes of bismuth (178, 179) have been prepared and spectroscopically characterized (176, 177, 180). Solid-state structures for examples of bis-(tropolonate) derivatives confirm the chelate interaction (171) and in the case of the nitrate derivative, reveal intermolecular alkoxide-bismuth [Bi-0 2.688 and 2.666 A] dimer contacts 52, which are slightly longer than the chelate bonds [Bi-0 2.130-2.323 A],... 

Ammonium cerium(IV) nitrate on reaction with acetone or acetophenone generates acetyl- or benzoylformonitrile oxides, respectively (99). These nitrile oxides dimerize to furoxans and give, in the presence of alkenes and alkynes, 3-acetyl- or 3-benzoyl-4,5-dihydroisoxazoles and 3-acetyl- or 3-benzoylisoxazoles, respectively the yield of the isoxazole derivatives was improved on using ammonium cerium(III) nitrate tetrahydrate-formic acid (99). 

---