2.3- dimethyl-4-nitrophenyl phenyl

Heine and co-workers693 prepared the adduct 5 from 2,2-dimethyl-4-phenyl-6-p-nitrophenyl-1,3-diazabicycIo [3,1,0]hex-3-ene (4) and DEAD in refluxing xylene acid hydrolysis gave (7). The aroylaziridine 6 with DEAD also gave 7 (14%), as did the oxazolin-5-one 8 and DEAD via the benzylpyrrole 9. 

The basicity of simple 4,5-dihydropyrazoles (A -pyrazolines) has been discussed on the basis of protonation at N-1 in the case of 1-unsubstituted, 1-methyl, and 1-phenyl derivatives <2000JP0372>. The pA values of 15 4,5-dihydropyrazoles substituted at N-1 by /i-nitrophenyl, 2,4-dinitrophenyl, and 2,4,6-trinitrophenyl groups were determined. After examining some linear free energy relationships, to discuss these values further, DFT calculations, including temperature effects, were carried out on the parent compounds (no C-substituents) for the 1-unsubstituted, 1-methyl, 1-phenyl, l-/)-nitrophenyl, and 1-(2,4,6-trinitrophenyl) series. These calculations predicted an inversion of N-1 and N-2 basicities between 1-phenyl- and l-(/>-nitrophenyl)-4,5-dihydropyrazoles. Since there were no experimental data for the protonation of 4,5-dihydropyrazoles in the gas phase, chemical ionization mass spectrometry was used to try to determine the structure of protonated 1-methyl- and l,3-dimethyl-5-phenyl-4,5-dihydropyrazoles. The substituent effects and protonation sites of 1-phenyl-3-methyl-5-A-benzylideneaminopyrazoles were studied by NMR and ab initio (6-31G ) MO calculations <1996J(P2)2383>. 

Bromation of l,3-dimethyl-7-phenyl-oxazolo[2,3-/]-purine-2,4-dione 49 (bromine in acetic acid), took place at position 6 (compound 50). Nitration with potassium nitrate in sulfuric acid did not take place at Cg but instead gave 7-(4-nitrophenyl)-oxazolo[2,3-/]purinedione derivate 51 due of the protonation of the oxazolo-purine ring system by acid. Alkylation at position 1 with ethyl iodoacetate in dimethylformamide in the presence of potassium carbonate gave 52 (90KGS1396) (Scheme 14). 

Di-O-methyl-A -(4-nitrophenyl)glucosylamine, D-739 Dimethyl-2-phenyl-l,3-dioxolane-4,5-dicarboxylate, T-12 A -(3,4-Dimethylphenyl)-L-ribitylamine, A-326... 

Reaction of carboxylate ion with nitrophenyl sulfites gives the carboxylate -nitrophenyl esters. If the -nitrophenyl sulfite is unsymmethcal (02NCgH40S(0)0R, where R is ethyl or phenyl), carboxylate attacks the -nitrophenyl side (69). Some amino acids react with methyl and benzyl sulfites in the presence of -toluenesulfonic acid to give methyl and benzyl esters of the amino acids as -toluenesulfonate salts (70). With alcohols, the conversion of henzil to a monoacetal upon addition of sulfuric acid to the henzil in methanol and dimethyl sulfite proceeds in high yield (71). 

Imidazole, 2-ethyl-1 -(o-nitrophenyl)-cyclization, S, 431 Imidazole, 4-ethyl-2-phenyl-oxidation, S, 405 Imidazole, ethynyl-Michael addition, S, 437 Imidazole, 4-ethynyl-2-phenyl-synthesis, S, 494 Imidazole, 1-formyl-reactions, S, 452 Imidazole, 2-formyl-mass spectra, S, 360 Imidazole, 4-formyl-synthesis, S, 475-476 Imidazole, 2-formyl-1,5-dimethyl-mass spectra, S, 360 3-oxide... 

The dehydrogenative condensation of unsaturated ketones with methyl ketones was used for preparing various series of 2,4,6-tri-arylpyrylium salts not only by Dilthey, but also by Wizinger and co-workers (for combinations of phenyl, p-anisyl, and p-dimethyl-aminophenyl substituents), by Amoros-Marin and Carlin (combinations of phenyl and p-chlorophenyl), by Le Fevre and Le Fevre (for combinations of pbenyl and m- or p-nitrophenyl), and by others. ... 

CN ( )-( )-l,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridinedicarboxylic acid 2-methoxyethyl 3-phenyl-2-propenyl ester... 

For species 11 we will use the intrinsic barrier for hydroxide addition to trimethyl phosphate, G = 19 (calculated using rate and equilibrium data from reference 100) and assume the same value for the attack of hydroxide at sulfur on dimethyl sulfate. This (nonobservable) rate will be estimated using a Brpnsted type plot from the rate constants for diaryl sulfates (diphenyl sulfate,and bis p-nitrophenyl sulfate), estimated from the rate for phenyl dinitrophenyl sulfate,assuming equal contributions for the two nitro groups. This gives ftg = 0.95, and thus for dimethyl sulfate log k = 11.3... 

Furthermore, in an extension of this study, the synthesis of a phenyl-thiophene (type II) containing four ortho substituted groups has been carried out 40), (41). To resolve a -linked phenylthiophene there was chosen a compound which met all the steric requirements in order that the proposed structure be capable of existing in enanthiomorphic forms. All these requirements seem to be met by 2,5-dimethyl-4-(6 -methyl-2 -nitrophenyl)-3-thenoic acid ... 

IsopropyI-4-nitrophenyl 2, 4-nitrophenyl 3, 2-methyl-3-nitrophenyl 4, 2-methyl-4-nitrophenyl 5, 3-fluorenyl 6, 1-fluorenyl 7, 2,6-dimethyl-4-nitrophenyl 8, 3-benzoyl-phenyl 9,4-benzoylphenyl 10,9-anthracenyl 11, 3-acetylphenyl 12,4-acetylphenyl 13, 1-naphthyl. 

Nitrobenzoylamino)-2,2-dimethylpropanamide (143 R = Me) reacts in methanol-DMSO solution with sodium methoxide to yield 5,5-dimethyl-2-(4-nitrophenyl)imidazol-4(5//)-one (144 R = Me). The 4-methoxyphenyl derivative and the parent phenyl derivative react similarly, as do compounds in which variation of the 2-substitutent (R = Pr , Ph, 4-O2NC6H4) was made. The mechanism of the cyclization probably involves initial formation of the anion of the alkanamide (145), which adds to the carbonyl group of the benzamido moiety to yield the tetrahedral oxyanion (146) proton transfer and dehydration then yield the heterocycle (144). The kinetics of hydrolysis in water at 70 °C and pH 2-11 of A-glycidylmorpholine (147) have been reported. ... 

Marubayashi et al. <1997J(P2)1309> have also shown that solid-state dimerization is possible and propose that there is a buffer zone in the crystal structure of 1,4-dihydropyridines that governs the solid-state photodimerization process. This is exemplified by the fact that dimethyl l,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)pyridine-3,5-dicar-boxylate 83 cannot undergo solid-state photodimerization (Equation 21), whereas the structurally related (4/ 3, l / 3 )-methyl-l-phenyl-2-piperidinoethyl-l,4-dihydro-2,6-dimethyl-4-(2-thienyl)pyridine-3,5-dicarboxylate 84 affords a single product 5 (Scheme 2). Interestingly, when the photodimerization conditions are applied to the corresponding solution-phase reaction, the sole product is that of aromatization giving product 85. 

One of the initial findings about bicyclic aziridines is reported in [88] the authors carried out the synthesis of 3,5a-dihydro-l//-azireno[l,2-c]imidazoles by reacting trwith carbonyl compounds in methanol saturated with ammonia in the presence of ammonium bromide. In particular, 2,2-dimethyl-6-(4-nitrophenyl)-4-phenyl-l,3-diazabicyclo[3.1.0]hex-3-ene 72 was obtained in the reaction of ketone 70 with ammonia and acetone 71 (Scheme 1.19). 

In nitric acid sulfuric acid, 3-methyl-1-phenylpyrazole yields the l-(4-nitrophenyl) derivative (96%), and 5-methyl-1-phenylpyrazole the l-(4-nitro-phenyl) derivative (98%). l-(2-Methylphenyl)- and 3,5-dimethyl-1-phenylpyrazole give low yields (up to 33%) of the 4-nitrophenyl products, but l-(2,6-dimethylphenyl) pyrazole gives l-(2,6-dimethyl-3-nitrophenyl) pyrazole (92%). The l-methyl-2-phenyl and 5-methyl-1-phenylpyrazolium cations are markedly less reactive than the 1-phenylpyrazolium cation, presumably because of steric hindrance to coplanarity of the rings. 

In the nitration of methylphenylpyrazoles, Parrini [57AC(R)929] showed that a mixture of nitric and sulfuric acids leads to nitration first in the para position of the phenyl ring and second in the 4-position of the pyrazole ring. 4-Nitro-(4-nitrophenyl) derivatives were obtained from 3,5-dimethyl-1-phenylpyrazole and 3-methyl-5-phenylpyrazole. 

The results of Katritzky and co-workers [74JCS(P2)382], who carried out an extended study of such systems, are shown in Fig. 10. These indicate that all six compounds studied reacted as the conjugate acid at high acidity. Three compounds also reacted as the conjugate acid at low acidity [3-methyl-4-nitro-l-phenylpyrazolin-5-one, 3-methyl-5-methoxy-4-nitro-l-phenyl pyrazole, and 3-methyl-5-methoxy-l-(4-nitrophenyl) pyr-azole]. The other three compounds [2,3-dimethyl-4-nitro-l-phenylpyraz-olin-5-one, 3-methyl-1-(4-nitrophenyl) pyrazolin-5-one, and 2,3-dimethyl-1-(4-nitrophenyl) pyrazolin-5-one] reacted as free bases at low acidity. 

The simple phenyl-substituted pyrazines do undergo nitration in the phenyl ring for example, 2-phenylpyrazine yields the 4-nitrophenyl derivative (mixed acid), although 5-phenyl-2-pyrazinone forms the 3-nitropyra-zinone under similar conditions (75MI1). However, 2,5-dimethyl-3,6-diphenylpyrazine and its /V,A -dioxide are both reported to be nitrated to give the bis-(3-nitrophenyl) products (55JCS3094). 

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