Nitrobenzoic esters

Recently, in extending the reaction to aliphatic glycols, Ghera observed that p-nitrobenzoate esters gave better results than acetates, and that zinc acetate could be substituted for activated zinc. He has proposed that the rearrangement is a heterogeneous catalytic process, with the zinc acting as a Lewis acid ... 

Chemical properties. As already stated, Petrin is an intermediate in the prepn of numerous mixed esters. Marans et al (Ref 2) prepd a series of Petrin-nitrobenzoate esters by reacting Petrin with the appropriate nitrobenzoyl chloride. They also prepd Petrin-formate, acetate, propionate, oxalate, glutarate, succinate, adipate, and phthalate. An especially important Petrin derivative is Petrin-acrylate. It is prepared by reacting Petrin with a mixt of acrylyl chloride and dimethylaniline (Ref 4)... 

As a final example in this section, we may consider the i/ .vo-di spl acernen l of the nitro group itself. Liu and Zhao68 have investigated the substitution of the nitro group in a series of 4-nitrobenzoate esters by the phenylthiolate anion. Here the process again involves radical species, but now it is the radical anions of the nitro compounds which are observed as well as the thiophenoxyl radical which could be trapped. 

Marans and co-workers used pentaerythritol trinitrate (81) to synthesize a number of aryl and alkyl esters, including the formate, propionate (84), oxalate, succinate, benzoate (85), 3,5-dinitrobenzoate (86), and ortho-, meta-, and para- (87) nitrobenzoate esters. The para-nitrobenzoate ester (87) has also been prepared from the nitration of pentaerythritol monobenzoate with mixed acid. ... 

After the nitric acid has been added, stirring is continued for fifteen minutes longer the mixture is then poured upon 1300 g. of cracked ice. The crude methyl m-nitrobenzoate separates as a solid and is filtered off by means of suction and washed with water. The product is placed in a flask and agitated with 200 cc. of ice-cold methyl alcohol in order to remove a small amount of o-nitrobenzoic ester and other impurities that are present. The cooled mixture is then filtered by means of suction, washed with another 100-cc. portion of cold methyl alcohol (Note 3), and the solid dried. Flic yield is 220-230 g. (81-85 Per cent of the theoretical amount) of an almost colorless product melting at 74-76°. In order to obtain a product of maximum purity, which melts at 78°, it is advisable to rccrystallize the ester from an equal weight of methyl alcohol,... 

Table 13 Sulfur Participation in the Solvolysis of rhiacycloalkyl p-Nitrobenzoate Esters in 80% Aqueous Acetone...

Deoxy-D-arafnno-hexose (55) was treated in methanol with hydrogen chloride according to a procedure79 which was purported to yield almost exclusively a mixture of the anomers of methyl 2-deoxy-D-arabino-hexofur anoside. It has now been shown78 that the latter consists, in fact, of an anomerically pure methyl 2-deoxy-D-arabino-hexofuranoside (77), plus substantial proportions of an approximately 1 1 mixture of methyl 2-deoxy-a- and jS-D-orabmo-hexopyranosides (78) and (79), and unreacted 2-deoxy-D-arabino-hexose (55). p-Nitrobenzoylation of the sirupy, quadripartite mixture led to a mixture of p-nitrobenzoic esters from which, by fractional recrystallization, there was obtained in pure form a methyl 2-deoxy-3,5,6-tri-O-p-nitrobenzoyl-D-arabino-hexoside (80). Attempts to replace, directly, the severely hindered methoxyl group at C-l of (80) by halide failed. 

Its p-Nitrobenzoate Ester, C17H21NOg, lt-yel ndls, mp 94° (dec) exploding on a spatula placed in a flame, was obtd by interaction of the hydroperoxide with p-nitrobenzoyl chloride at 0° for 5 hrs (Ref 4)... 

The position of the equilibrium of Eq. (13) depends markedly on the nature of R. When R = H the product is entirely the ketone, whereas when R = CH3 the product can be shown from IR and NMR spectroscopic data to be completely enolized. Whichever form predominates, Schotten-Baumann benzoylation gives the indolizine / -nitrobenzoate ester (67). Acetic anhydride instead of perchloric acid with 65 gives the 1-acetamidoindolizine which is also available from the 1-acetyl compound via the Schmidt reaction. 

In another study (117), hydride reduction (LiBHlsec-BuJg ) of the -nitro-benzoate diketone 409 gave the carbonate enone lactone 410 in high yield. Reduction of -nitrobenzoate ester must have produced the hemi-ketal inter-... 

The oxirane fused azepine 40, formed by an intramolecular [5+2] cycloaddition reaction undergoes an acid promoted rearrangement to yield the tricyclic derivative 41. The structure was confirmed by X-ray crystallography of the nitrobenzoate ester <07OL4681>. 

Enantiomeric cyclic amides and imides, esters, ketones, 8- and 7-lactones, and alkyl-substituted indenes can be resolved on CTA-I without derivatization. Chiral alcohols can also be resolved without deiivatiza-tion, but the best results are obtained when they are converted to esters. In general, para-nitrobenzoic esters are recommended if the hydroxyl group is directly attached to the stereogenic center benzoate or para-biomobenzoate... 

Heating widdrol (5) in 80% aqueous dioxane, containing 0.02 M perchloric acid, or solvolysis of its 4-nitrobenzoate ester in dry dioxane containing lithium perchlorate trihydrate, afforded... 

The nitrobenzoate ester (6.80 g, 12.0 mmol) in a mixture of THF/MeOH (10 mL 300 mL), containing powdered sodium hydroxide (1.56 g, 39.0 mmol), was stirred at room temperature for 15 min. The reaction was concentrated under reduced pressure, and the residue was partitioned in ether/water (100 mL, 1 1 by volume). The layers were separated, and the aqueous portion was extracted with ether (3 x 50 mL). The combined organic extracts were washed with brine, dried (MgSO4), filtered, and concentrated under reduced pressure. The crude residue was piii ilied by flash chromatography eluting with 5% ether/hexanes to provide 5.00 g (99%) of the inverted alcohol as a clear oil. 

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