Ethyl benzoate, reduction

NOTE. Many esters reduce Fehling s solution on warming. This reduction occurs rapidly with the alkyl esters of many aliphatic acids, but scarcely at all with similar esters of aromatic acids (f.g., ethyl oxalate reduces, but ethyl benzoate does not). Note also that this is a property of the ester itself thus both methyl and ethyl oxalate reduce Fehling s solution very rapidly, whereas neither oxalic acid, nor sodium oxalate, nor a mixture of the alcohol and oxalic acid (or sodium oxalate), reduces the solution. 

This gradation is illustrated by the results obtained with the diazonium salts from the isomeric aminobenzoic adds. When the orthQ diazonium nitrate is treated with absolute ethanol only reduction occurs 23 ethyl benzoate is obtained in 63% yield.f The diazonium add sulfate derived from ra-aminobenzoic add is converted into a mixture of ethyl benzoate and ethyl m-ethoxybenzoate, the former preponderating.24 23122 Finally, with the p-diazonium salts the ether reaction is the favored one 22123 from the nitrate the yields of p-ethoxy benzoic add and ethyl benzoate are 60% and 12%, respectively. 

Dimsylsodium (24) functions as a highly basic sulfur ylide. It can be used to convert phosphonium salts to phosphorus ylides for use in the Wittig reaction. Dimsylsodium also reacts with aldehydes and ketones by nucleophilic addition to form epoxides and with esters by nucleophilic substitution to yield p-ketosulfoxides (25) (Scheme 11). The p-ketosulfoxides (25) contain acidic a-hydrogens which can be readily removed to allow alkylation, and the products (26) suffer reductive desulfuration on treatment with aluminium amalgam to yield ketones (27) (Scheme 11) This procedure can, for instance, be applied to the conversion of ethyl benzoate to propiophenone (28) (Scheme 12). 

The initial compound (9) was prepared by stirring 1,3,5 trimethoxybenzene with 1 -methyl-4-piperidone in glacial acetic acid. The tram alcohol (10) was obtained by hydration of the double bond and the corresponding cis compound (11) then made via the ketone by oxidation then reduction. Treatment with acetic anhydride and an acid catalyst such as boron trifluoride etherate gave (12). Treatment of this compound at room temperature with ethyl benzoate in the presence of sodium metal produced the diketone (13) which was cyclised to (14) by the addition of mineral acid. Final demethoxylation of the chromone hydroxy groups with pyridine hydrochloride was carried out for several hours at 180°. 

Examples of nonequimorpholytic selectivity include the selective reduction of ethyl benzoate... 

Which aldehyde is an intermediate in the reduction of ethyl benzoate with lithium aluminum hydride ... 

Write out the reaction for the LiAlH reduction of ethyl benzoate to benzyl alcohol. 

Al-amalgam in alcohol has been found to be an efficient reagent for a simple reduction of esters to alcohols.— E A soln. of 30 g. ethyl benzoate in 95%-ethanol treated at 70° with Al-amalgam, thoroughly shaken, water added to maintain the temp, at ca. 75°, and the product isolated when all of the Al-amalgam has reacted 20 g. benzyl alcohol. F. e. s. J. N. Ray, A. Mukherji, and N. D. Gupta, J. Indian Chem. Soc. 38, 705 (1961). 

In U.S. Patent 4,174,429 [54], Montedison characterized a large number of Mg/Ti/Cl/electron donor complexes based on a wide variety of ligands such as ethyl acetate, ethanol, ethyl benzoate, benzonitrile, ethylene carbonate, n-butyl acetate and diethyl ether, using TiClj prepared from hydrogen reduction of TiCl. ... 

Another important transformation, the reduction of esters to aldehydes with lithium diisobutyl-tert-butoxyaluminum hydride (LDBBA) in flow, was performed in the laboratory of Janssen Pharmaceuticals [45]. DIBAL-H applied in their previous research [44] proved to be unsuccessful in reducing ethyl benzoate (la) to benzaldehyde (2a). LDBBA appeared to be the most general and effective alternative to DIBAL-H. The selective reduction of an ester group in the presence of an aldehyde, the selective reduction of a single ester group, and the selective reduction of a primary ester in the presence of a secondary ester are achieved with the efficiency that cannot be achieved under traditional batch conditions. 

Birch reductions of alkyl benzoates are not normally feasible due to the preference for Bouveault-Blanc-type reduction of the ester group. However, it has now been found that if one to two equivalents of water are added to the ammonia before addition of the metal, then good yields of cyclohexadiene-esters [e.g. (191) from ethyl benzoate] can be realised. It is known that Birch reductions of benzoic acids can be used to generate dianonic species (192). These have been found to undergo conjugate additions to methyl acrylate and... 

Reduction of ethyl 3-[(2-fcrf-butoxycarbonylperhydropyrido[l,2-a]pyra-zin-7-yl)methoxy]benzoate with LAH in THF at room temperature yielded... 

Whereas ethyl l-thio-d-D-arabinofuranoside cannot be prepared directly, the 5-O-benzoyl diethyl dithioacetal gave 38% of ethyl 5-O-benzoyl-l-thio-0-D-arabinofuranoside, which was debenzoylated to the desired product. The 5-benzoate of ethyl 1-thio-a-D-ribofuranoside was similarly prepared.88 Two other compounds, ethyl 2-acetamido-2-deoxy-l-thio-/3-L-arabino-furanoside72 and ethyl 2-acetamido-2-deoxy-l-thio-a-D-xylofuranoside,73 were prepared from the corresponding d-galacto and d-gluco analogs by periodate oxidation, and subsequent borohydride reduction of the product. 

Voltammetric data for ester reductions are available for several aromatic esters [51-54], and in particular cyclic voltammetry shows clearly that in the absence of proton donors reversible formation of anion radical occurs [51]. In dimethylfonnamide (DMF) solution the peak potential for reduction of methyl benzoate is —2.29 V (versus SCE) for comparison dimethyl terephthalate reduces at —1.68 V and phthalic anhydride at —1.25 V [4]. Half-wave potentials for reduction of aromatic carboxylate esters in an unbuffered solution of pH 7.2 are linearly correlated with cr values [51] electron-withdrawing substituents in the ring or alkoxy group shift Ei/o toward less negative potentials. Generally, esters seem to be more easily reducible than the parent carboxylic acids. Anion radicals of methyl, ethyl, and isopropyl benzoate have been detected by electron paramagnetic resonance (epr) spectroscopy upon cathodic reduction of these esters in acetonitrile-tetrapro-pylammonium perchlorate [52]. The anion radicals of several anhydrides, including phthalic anhydride, have similarly been studied [55]. 

Other reductions. Miller et report reduction of benzoic acid and of methyl benzoate to benzyl alcohol and of n-butyl caproate to n-butanol and n-hexanoL Russian investigators" report reduction of aliphatic and aromatic esters to aldehydes, of ortho esters to acetals, of acetals to ethers, and of benzyl ethyl ether to toluene. 

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