Nitro benzaldehydes

These have been reviewed in an earlier volume. -Nitro-benzaldehyde has also been prepared in 32% yield by heating /)-nitrobenzyl chloride with potassium fer/-butylperoxide. The... 

Dimethylsulfan-Boran reduziert 4-Nitro-benzoylchIorid zu 4-Nitro-benzaldehyd (60% d.Th.)5. 

Formyl-cyclohexan 4-Chlor-benzaldehyd 4-Nitro-benzaldehyd Zimtaldehyd... 

Je nach Bedingungen kann auch Hexaathyl-disiloxan entstehen. Die bei 20° ablaufende Reaktion ist stark strukturabhangig. Elektronenliefernde Substituenten fordern, elektro-nenanziehende erschweren die Reduktion. So wird 4-Nitro-benzophenon z.B. erst inner-halb 47 Stdn. zu 4-Nitro-diphenylmethan reduziert, wahrend 4-Nitro-benzaldehyd und -acetophenon nicht bis zu Kohlenwasserstoffen reduziert werden. 

Auf ahnliche Weise erhalt man aus 2-Nitro-benzaldehyd in waBrig-alkoholischer Ace-tatpuffer-Losung Benzo-[c]-l,2-oxazol (51% d.Th.)1 ... 

Novel chiral thiolated amino alcohols have been recently synthesised and then evaluated by Vilaivan el al. as a potential new class of ligands for Cu-catalysed nitroaldol reactions. Amino alcohol ligands bearing Ai-(2-alkyl-thio)benzyl substituents provided only modest enantioselectivities (22-46% ee) while those carrying Al-2-thienylmethyl substituents provided better enantioselectivities of up to 75% ee for the nitroaldol reaction between p-nitro-benzaldehyde and nitromethane. A range of aromatic aldehydes were acceptable substrates giving moderate to high enantioselectivities of up to 88% ee, as shown in Scheme 10.32. 

Using 2,6-diformyl-4-methylphenol dioxime, Tasker, Schroder, and their co-workers conducted a magnetostructural study on complex (374) (pseudo macrocyclic structure Cu-Cu 2.994 A 2J= — 904 cm-1).330 Using 2-hydroxy-5-nitro-benzaldehyde benzoylhydrazone as ligand, complex (375) (Cu-Cu 3.041 A 2J=—372cm 1) was reported.331 Using 3-formylsalicylic acid oxime Okawa and co-workers reported complex (376) (square-planar and SP geometry Cu-Cu 2.961 A).332... 

A. tn-NUrocinnamic acid. In a 1-1. round-bottomed flask fitted with a reflux condenser are placed 151 g. (1 mole) of tw-nitro-benzaldehyde (Note 1), 115 g. (1.1 moles) of malonic acid, 250 ml. of 95% ethanol, and 25 ml. of pyridine. The mixture is heated on a steam bath under gentle reflux for 6-8 hours and cooled. The large masses of crystals are broken up with a spatula, and the reaction mixture is cooled in an ice bath. The solid is collected on a Buchner funnel, and the residue is washed with 100 ml. of cold ethanol and then with two 100-ml. portions of diethyl ether. The crude w-nitrocinnamic acid is suspended in 300 ml. of ethanol and digested on a steam plate for 2-3 hours. The mixture is cooled and filtered, and the solid is air-dried. The product, 144 155 g. (75-80%), is a light-yellow solid and melts at 200-201° (Note 2). 

Nitro compounds have also been reported to undergo photocyclizations. The intermediacy of an isoxazoline in the photorearrangement of o-nitro-benzaldehyde to o-nitrosobenzoic acid is now in doubt,318 but intramolecular hydrogen abstraction by an excited nitro group in nitrobenzene derivatives can result in the formation of heterocycles. 4-tm-Butyl-3-methoxy-2,6-dinitrotoluene (384) on irradiation in methanolic sodium hydroxide solution... 

For the reduction of nitro-compounds containing a group which may be attacked by nascent hydrogen, as, for example, an aldehyde group, an unsaturated side chain, and so on, special methods must he applied. In such cases ferrous hydroxide or iron powder (cf. Chap. VII. 5, arsanilic acid) are often used. The reduction is carried out thus a weighed amount of ferrous sulphate is caused to act, in the presence of alkali (potassium or sodium hydroxide, baryta), on the substance to he reduced. In this way it is possible to reduce, for example, o-nitro-benzaldehyde to aminobenzaldehyde, and o-nitrocinnamic acid to amino-cinnamic acid. 

Benzaldehyde, 4-(l, l-dimethylethyl)-3-nitro Benzaldehyde, 4-(l, l-dimethylethyl)-3,5-dinitro Benzene, 2-(l,l-dimethylethyl)-4,5 dimethyl-1, 3-dinitro Benzoic acid, 4-(l,l-dimethylethyl)-2methyl 3,5-dinitro Benzene, l(l,l-dimethylethyl)-3,4-dimethyl-6- (lmethylethyl)-... 

Benzene, 2-ethyl-5-isooctyl-4-methoxy-l, 3-dinitro Benzene, l-isoheptyl-2-methoxy-4-methyl-3, 5-dinitro Benzene, l-isooctyl-2-methoxy-4-methyl-3, 5-dinitro Ethanone, 1- [3-(l,l-dimethylethyl)-2-methoxy-5-nitrophenyl Benzene, 1,3-dibromo-2-isopropyl-5-methoxy-4-nitro Benzene, 1,3-BIS- (1, l-dimethylethyl)-5-nitro Benzaldehyde, 5 (l,l-dimethylethyl)-2-methoxy-3-nitro Benzene, 1, 5-BIS- (1, l-dimethylethyl)-2 methoxy-4 methyl... 

CHO Arcl 96 -20 3-Acetoxy-2-chlor-4-meth- oxy-5-nitro-benzaldehyd 72 86-88 (Ether) 4... 

Die aus Formaldehyd, Benzaldehyd oder 4-Nitro-benzaldehyd und 2-Phenyl-ethylaminen erhaltlichen Imine gehen bei der N-Acylierung mit Acyl-chloriden oder Carbonsauren/ Thionylchlorid direkt oder nach Erhitzen der N-Acyl-iminium-Zwischenstufe in 2-Acyl-1,2,3,4-tetrahydro-isochinoline iiber3, die nach den iiblichen Methoden (Bd.XI/1, S. 926) zu denfreien 1,2,3,4-Tetrahydro-isochinolinen hydrolysiert werden konnen. 

Much more spectacular were the selectivity variations in the case of 3-nitro-benzaldehyde reduction (Table 3). Depending on the hydrogen donor used 3-nitro-benzyl alcohol (methanol, 450°C) or 3-aminobenzaldehyde (i-propanol, 450°C) were the main reaction products. 

HC.CgH4.N( N)Cl. Its stannic chloride salt, [20HC.C6H4.N( N)CDSnCl4], col ndls, mp expl mildly on heating in a flame was prepd from 3-nitro-benzaldehyde, stannous chloride in coned HC1 and Na nitrite, as described in Refs 1 2 Refs I)Beil 16,538 2)F.Tiemann R.Ludwig,... 

N 27.60% yel crysts, mp 240 242° insol in common org solvs was prepd by reacting the hydrobromide of N,N -diamino-guanidine and m-nitro-benzaldehyde in ale. It forms salts, such as the Hydrobromide, C1SH, 3N704+HBr, yel pdr,gradually reddens in the air and dec at 292°. Other props are given in the Refs. The expl props of the compd and its salts were not detd... 

Very pure material can be obtained by dissolving o-nitro-benzaldehyde in toluene and precipitating with petroleum ether, according to earlier instructions.3... 

The amines 3 reported by Morao and Cossio also constitute neutral dendritic catalysts without metal sites they consist of a simple amine core functionalised with Frechet dendrons (Fig. 6.44) [74]. Such amines can catalyse the nitroaldol or Henry reaction [75] between aromatic aldehydes and nitroalkanes. Whereas neither the yield nor the stereoselectivity (syn/anti 1 1) of the reaction of p-nitro-benzaldehyde with nitroethane was found to change on use of different generations of dendritic catalysts, a distinctly negative dendritic effect was observed in the reaction of benzaldehyde with 3-nitro-l-propanol. Catalysts 3 a and 3 b gave... 

The first chiral catalysts were developed from achiral molecules such as DABCO, quinuclidine, indolizine or pyrrolizine-derived catalysts by introducing asymmetric functions. Hirama and co-workers examined chiral C2-symmetric 2,3-disubstituted l,4-diazabicyclo[2.2.2]octanes such as 2,3-(dibenzoxymethyl)-DABCO (29) as catalysts for asymmetric MBH reaction between 4-nitro-benzaldehyde 27 and methyl vinyl ketone (MVK, 28) (Scheme 5.6) [57]. The additive function of the catalyst compared to the achiral DABCO resulted, however, in diminished reactivity, and the reaction required high pressure in order to... 

Because the phosphonate-phosphate rearrangement requires P-C bond breakage and formation of the P-O bond kinetic isotope studies by means of 13C NMR were chosen.50 13C KIEs were derived from NMR analysis of substrate-o-nitro-benzaldehyde or product-phosphate. Samples of aldehyde were prepared using the dead-end method. To the solution of phosphite 3 and triethylamine in acetonitrile an excess of aldehyde was added and solution was heated at 65°C to complete conversion of phosphonate 4 to phosphate 5 monitored by 31P NMR. The aldehyde conversions 0.2-0.8 were calculated from the balance of concentrations. The changes of 13C composition were determined for carbonyl carbon atom using signal of meta aryl carbon as an internal standard. KIE 1.0223(14) was calculated from the slope of linear relationship of isotopic ratio R and fraction of reaction,... 

Methyl groups in the 3- and 4-positions are unreactive toward aldehydes,68 110 but 5-methylisothiazoles condense with 3-nitro-benzaldehyde. This property has been used to separate pure 3,4-dimethylisothiazole from a mixture with 3,5-dimethylisothiazole.110... 

The electron-withdrawing nitro group in p-nitro-benzaldehyde polarizes the carbonyl group. 

The second-order rate constants for the reaction of OH radical with meta- and para-isomers of hydroxy-, methoxy-, chloro- and nitro-benzaldehydes are in the range (2.8 to 12) x 10 dm mol s . The higher rate in methoxybenzaldehyde is attributed to the activation of the ring by the electron-donating -OCH3 group. 

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