2-Ethyl pentanoic acid

An important example of this reaction is the malonic ester synthesis, in which both Z groups are COOEt. The product can be hydrolyzed and decarboxylated (12-38) to give a carboxylic acid. An illustration is the preparation of 2-ethyl-pentanoic acid from malonic ester ... 

Hexanol Heptanoic acid (87 %) 2-Methyl hexanoic acid (10%) 2-Ethyl pentanoic acid (3 %) 0.1... 

C10H17NO2 2-cyano-3-ethyl-pentanoic acid ethyl ester 28456-66-8 ... 

The sequence begins with a Claisen condensation of ethyl pentanoate to give a p keto ester The ester is hydrolyzed and the resulting p keto acid decarboxylates to yield the desired ketone... 

Electrochemical fluorination of a-cyclohexenyl-substituted carboxylic (acetic, propanoic, butanoic, and pentanoic) acid esters (methyl, ethyl, and propyl) results in a series of both perfluoro-9-alkyl-7-oxabicyclo[4 3 OJnonanes and per-fluoro-8-alkoxy-9-alkyl-7-oxabicyclo[4.3.0]nonanes [<8S] (equation 19)... 

Although irinotecan metabolism generates at least 20 metabolites, many of them are found at trace levels in patients. Clinically relevant metabolites of irinotecan are the active metabolite 7-ethyl-10-hydroxycamptothecin (SN-38), inactive glucuro-nide SN-38G, and inactive aminopentane carboxylic acid (7-ethyl-10[4-N-(5-amino-pentanoic acid)-l-piperidino]carbonyloxycamptothecin, APC) (Figure 14.5). 

Acetic acid, methyl ester Acetic acid, ethyl ester Pentanoic acid, methylethyl ester Acetic acid, methylethyl ester Acetic acid, 3-propenyl ester Acetic acid, benzyl ester Oxalic acid, dimethyl ester Oxalic acid, diethyl ester Oxalic acid, fe(l-methylethyl) ester... 

Ethyl levulinate Pentanoic acid, 4-oxo-, ethyl ester (539-88-8), 75, 129 ( )-3-Ethyl-1-oxaspiro[3.5]nonan-2-one, 75, 119... 

A still different scheme is used for the preparation of the benzimidazole buterizine (74). Alkylation of benzhydrylpiperazine with substituted benzyl chloride 70 gives the intermediate 7U Nucleophilic aromatic displacement on this compound by means of ethyl amine leads to reduction of the nitro group then gives the diamine T. Treatment of that with the orthoformate ester of pentanoic acid serves to form the imidazole ring. There is thus obtained the peripheral vasodilating agent buteri zi ne (74). ... 

The ethyl sec,-butylmalonate was prepared from sec-butyl bromide and malonic ester according to the general method described in Org. Syn. 4, n. The yield of ester boiling at i24-i32°/28 mm. was 80-81 per cent of the theoretical amount. The yields of 3-methyl pentanoic acid given in this procedure were obtained with this grade of ester. 

Hydroxy-6-methoxybenzaldehyde (16.875 g, 0.111 M), ethyl 5-bromopentanoate (23.25 g, 17.6 ml, 0.111 M), anhydrous potassium carbonate (16.5 g), sodium iodide (0.675 g) and 95% ethanol (150 ml) were refluxed with stirring (16 hours). The cooled reaction mixture was filtered and the solid washed well with ethanol. The filtrate was evaporated to dryness and the residue partitioned between ether and water. The ethereal layer was separated and washed with 2 N sodium hydroxide solution, water, dried (sodium sulfate) and evaporated. The residue was dissolved in 95% ethanol (300 ml) and 0.66 N sodium hydroxide solution (450 ml) and stirred at ambient temperature (4 hours). The reaction mixture was evaporated to half volume and diluted with water. The mixture was extracted once with ether and the aqueous layer acidified with concentrated hydrochloric acid with cooling. The crystalline solid formed was filtered off and washed well with water. Recrystallisation from ethyl acetate-petrol gave 5-(2-formyl-3-methoxyphenoxy)pentanoic acid, melting point 99-101°C. 

A mixture of ethyl 5-(2-formyl-3-benzyloxyphenoxy)pentanoate (3.61 g, 0.01 M), potassium hydroxide (1.19 g, 0.021 M) and ethanol (40 ml) were stirred at 50°-60°C for 5 hours. The ethanol was then removed in vacuum, the residue dissolved in water (50 ml) and the solution extracted with ether (2 x 80 ml). The aqueous layer was then acidified by the addition of 2 N aqueous hydrochloric acid and the product extracted with ether, and the combined extracts washed with water to neutrality, dried, and concentrated in vacuum to give 5-(2-formyl-3-benzyloxyphenoxy)pentanoic acid, 3.0 g, 91% as a yellow oil which crystallized on standing. The crude solid was crystallized from benzene/petroleum ether to give pale cream crystals, melting point 110°C. 

The mass spectrum of pentanoic acid is given in Figure 20-7. The base peak at m/z 60 corresponds to the fragment from loss of propene via the McLafferty rearrangement. The strong peak at m/z 73 corresponds to loss of an ethyl radical with rearrangement to give a resonance-stabilized cation. 

The mass spectrum of pentanoic acid shows a weak parent peak, an even-numbered base peak from the McLafferty rearrangement, and another strong peak from loss of an ethyl radical. 

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