P-nitrostyrene oxide

Using this crude mung bean preparation, the production of (R)-p-nitrostyrene oxide was achieved in 82% ee and 83.5% yield. After recrystallization, greater than 99% ee was achieved. 

Scheme 11. Deracemization of p-nitrostyrene oxide and application to the synthesis of (R)-nifenalol...

The electronic influences aftcoting the course of this reaction are further illustrated by the behavior of p-ratrobenzaldehyde (Eq. 264), which yields p-nitrostyrene oxide in moderate amounts,41- 44 whereas benxnldebyde iteolf (Eq. 263) gives aoetophenone exclusively.1<9-1... 

TABLE 8.3 Selected Kinetic Resolutions of rac-p-Nitrostyrene Oxide ... 

This method is very useful for the construction of 1-substituted 3,4-dihydroisoquinolines, which if necessary can be oxidized to isoquinolines. A P-phenylethylamine (l-amino-2-phenylethane) is the starting material, and this is usually preformed by reacting an aromatic aldehyde with nitromethane in the presence of sodium methoxide, and allowing the adduct to eliminate methanol and give a P-nitrostyrene (l-nitro-2-phenylethene) (Scheme 3.17). This product is then reduced to the p-phenylethylamine, commonly by the action of lithium aluminium hydride. Once prepared, the p-phenylethylamine is reacted with an acyl chloride and a base to give the corresponding amide (R = H) and then this is cyclized to a 3,4-dihydro-isoquinoline by treatment with either phosphorus pentoxide or phosphorus oxychloride (Scheme 3.18). Finally, aromatization is accomplished by heating the 3,4-dihydroisoquinoline over palladium on charcoal. 

Petri, A., Marconcini, P. and Salvadori, P. (2005) Efficient immobilization of epoxide hydrolase onto silica gel and use in the enantioselective hydrolysis of racemic para-nitrostyrene oxide. J. Mol. Catal. B Enzymatic, 32, 219. 

A variety of reducing agents have been used to reduce nitroarenes to azo compounds. However, a mixture of zinc and sodium hydroxide is used most frequently. - Reduction under these conditions produces hydrazo compounds, which are then oxidized to azo compounds by dissolved atmospheric oxygen alternatively, air can be drawn through the product solution to achieve the conversion. - Occasionally, activation of the zinc dust is required prior to its use, and, since metal ions form chelated complexes with azo compounds, a vigorous post-treatment with acids is recommended. The zinc-sodium hydroxide reduction conditions are sufficiently mild that p-nitrostyrene (2 equation 2), can be reduced without reduction of the vinyl groups. ... 

The pH-independent reactions of /7-methoxystyrene oxide and of /7-nitrostyrene oxide have different mechanisms than those for reactions of styrene oxides without strongly electron-donating or strongly electron-withdrawing groups. Both of these compounds are much more reactive than predicted from a Hammett sigma-rho plot of log k0bsd versus a for the pH-independent reactions of styrene oxide and its p-methyl and p-chloro derivatives.41 The most likely explanation for the enhanced reactivity of /7-nitrostyrene oxide is that attack of water at the /j-carbon, which is... 

Nitrous oxide, compressed Nitrous oxide, refrigerated liquid. See Nitrous oxide (2-Nitrovinyl) benzene. See P-Nitrostyrene Nitroxanthic acid. See Picric acid Nix Stix L478] Nix Stix L0582. See. Silicone emulsion... 

Acenaphthene 6-Acetoxy-2,4-dimethyl-m-dioxane Alkyl dimethyl ethylbenzyl ammonium chloride 2-Amino-4-chloro-6-nitrophenol Ammonium polysulfide Ammonium thiosulfate Anilazine Aniline Arsenic pentoxide Basic yellow 2 Bromoacenaphthylene 3-Bromochloro-5,5-dimethyl hydantoin p-Bromo-p-nitrostyrene Cadmium Cadmium chloride Calcium oxide Calcium polysulfide Carvacrol Cetalkonium chloride Cetethyidimonium bromide... 

Acrylonitrile Bioresmethrin 1,4-Bis (bromoacetoxy)-2-butene Boron oxide p-Bromo-P-nitrostyrene... 

Pyridone and />-nitrostyrene oxide give l- 8-hydroxy-i5 p-nitrophenethyI)-2-... 

The morpholine-promoted reaction of Af-alkyl piperi-dine-4-one with malonodinitrile and p-nitrostyrene derivatives in refluxing EtOH directly led to substituted tetrahydroisoquinoline derivatives in moderate to good yields [121], The reaction is initiated by a Knoevenagel condensation, in which a Michael addition/Thorpe-Ziegler sequence follows. Oxidation by air is the last step to occur providing the desired products. 

The mechanism and origin of enantioselectivity has been evaluated for a bicyclic guanidine-catalyzed phospha-Michael reaction between diphenyl-phosphine oxide and p-nitrostyrene by DFT calculations (Scheme 32). The catalyst was found to be involved in all three steps of the catalytic cycle proposed. 

Caldarelli et al. (240) have recently reported a five-step synthesis of substituted p)Trole libraries L22 and L23 using solid-supported reagents and scavengers. The synthesis involved oxidation of benzyl alcohols Mi to aldehydes (step a, Fig. 8.46), Henry reaction of aldehydes 8.91 with nitroalkanes M2 (step b), and acylation and elimination of nitroalcohols 8.93 (steps c and d) to give the nitrostyrenes 8.94, which were subjected to 1,3-dipolar cycloaddition with an isocyanoacetate (step e) to give the pyrroles 8.95. N-alkylation of these pyrroles with alkyl halides (step f) and final library-from-a-library hydrolysis/decarboxylation of L22 gave a library of trisub-stituted pyrroles L23 (step g. Fig. 8.46). 

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