Nitrostyrenes 1-nitrostyrene

The above are examples of the Claisen - Schmidt reaction. The formation of p-nitrostyrenes by reaction of nitroalkanes with aromatic aldehydes in the presence of aqueous alkali may be included under the Claisen- hmidt condensation ... 

It is of interest to note that reduction of p-nitrostyrene with lithium aluminium hydride (compare Section VI, 10) gives p-phenylethylamine CgHgCHjCHjNHj. 

Chapter IV. a-Chloromethylnaphthalene (IV,23) benzylamine (Gabriel synthesis) (IV,39) i r.N -dialkylanilines (from amines and trialkyl orthophosphates) (IV,42) a-naphthaldehyde (Sommelet reaction) (IV,120) a-phenyl-cinnamic acid (Perkin reaction using triethylamine) (IV,124) p-nitrostyrene (IV,129) p-bromonaphthalene and p naphthoic acid (from 2 naphthylamine-1 -sulphonic acid) (IV,62 and IV,164) diphenic acid (from phenanthrene) (IV,165). 

Internal nitroalkenes can be reduced to the corresponding ketox-imes by SnCla. The second method is a modification of the first, also allowing terminal nitroalkenes (such as nitrostyrenes) to be reduced to aldoximes. The oximes, in turn, can either be reduced to the corresponding amines, or cleaved to form the carbonyl compound. 

A two-step synthesis of indoles from o-nitrobenzaldehydes proceeds by condensation with nitromcthanc followed by reductive cyclization. Like the Leim-gruber Batcho method, the principal application of the reaction is to indoles with only carbocyclic substituents. The forniation of the o,p-dinitrostyrenes is usually done under classical Henry condensation conditions but KF/18-crown-6 in propanol was found to be an advantageous reaction medium for acetoxy-substituted compounds[1]. The o,p-dinitrostyrenes can also be obtained by nitration of p-nitrostyrenes[2]. 

Retrosynthetic path e in Scheme 2.2 requires a regioselective oxidation of an o-nitrostyrene to the corresponding phenylacetaldehyde. This transformation has been accomplished hy Wacker oxidation carried out in such a way as to ensure the desired regioselectivity. The required o-nitrostyrenes can be prepared by Heck vinylation. One procedure for oxidation uses 1,3-propaiiediol to trap the product as a l,3-dioxane[15]. These can then be hydrogenated over Rh/C and cyclized by treatment with dilute HCl,... 

Several procedures have been explored for the reductive cyclization of o-nitrostyrenes. Triethyl phosphite accomplishes this transformation by deoxy-... 

Ring closures which depend on the conversion of the heteroatom into an electrophile are mostly associated with the formation of thiophene, selenophene and tellurophene rings and some illustrative examples are shown in Scheme 17. The last example which concerns the conversion of reaction with isocyanides is of particular interest since it appears to entail the attack of an electrophilic nitrogen species on the aryl ring. 

Most ring syntheses of this type are of modern origin. The cobalt or rhodium carbonyl catalyzed hydrocarboxylation of unsaturated alcohols, amines or amides provides access to tetrahydrofuranones, pyrrolidones or succinimides, although appreciable amounts of the corresponding six-membered heterocycle may also be formed (Scheme 55a) (73JOM(47)28l). Hydrocarboxylation of 4-pentyn-2-ol with nickel carbonyl yields 3-methylenetetrahy-drofuranone (Scheme 55b). Carbonylation of Schiff bases yields 2-arylphthalimidines (Scheme 55c). The hydroformylation of o-nitrostyrene, subsequent reduction of the nitro group and cyclization leads to the formation of skatole (Scheme 55d) (81CC82). 

A convenient route to A -isoxazoline N-oxides has been developed from nitrostyrenes using dimethylsulfoxonium methylide. The addition of the ylide (572) to the nitrostyrene (571) was greatly facilitated by the presence of copper(I) salts, the isoxazoline N-oxide (573) being obtained in excellent yield (76JOC4033). 

Irans-P-Nitrostyrene [5153-67-3] M 149.2, m 60°. Crystd from absolute EtOH, or three times from benzene/pet ether (b 60-80°) (1 1). 

Nitrostyrene [100-13-0] M 149.2, m 20.5-21°. Crystd from CHCl3/hexane. Purified by addition of MeOH to ppte the polymer, then crystd at -40° from MeOH. Also crystd from EtOH. [Bemasconi et al. J Am Chem Soc 108 4541 1986.]... 

Figure 2.9. NMR spectra of 3,4-dimethoxy-p-methyl-p-nitrostyrene (9) [CDCI3, 25 C, 20 MHz], (a, b) H broadband decoupled, (a) complete spectrum with CH3 quartets at Sc = 14.1 and 56.0 (b, c) decoupled and coupled partial spectrum of benzenoid and alkene carbon atoms, (c) obtained by gated decoupling...

From the HH COSY contour plot 12a it can be established which cycloadduct has been produced from l-(iV,iV-dimethylamino)-2-methylbuta-1,3-diene and tra 5-P-nitrostyrene. The Jhh coupling constant in the one-dimensional H NMR spectrum 12b can be used to deduce the relative configuration of the adduct. 

Trimethylsilyloxy-p-nitrostyrene was the target of Knoevenagel condensation of 2-trimethyl-siloxybenzaldehyde with nitromethane in the presence of -butylamine as base. NMR spectra 20 were obtained from the product of the reaction. What has happened ... 

Chlorophenylacetic acid has been prepared from mandeloni-trile and hydrochloric acid in a sealed tube, from mandelic acid and hydrochloric acid in a sealed tube/ from a-nitrostyrene and hydrochloric acid in a sealed tube, from phenylglycine, hydrochloric acid, and sodium nitrite, from mandelic acid and phosphorus pentachloride (to give the acid chloride which is then hydrolyzed), and, in poor yield, from mandelic acid and thionyl chloride. In the method described, ethyl mandelate is prepared according to Fischer and Speier. The conversion to the chloroester and the acid hydrolysis step are modifications of a preparation described by McKenzie and Barrow. ... 

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