Methyl 5-oxopentanoate

The third synthesis of lasubine II (6) involves stereoselective intramolecular nitrone cycloaddition as a key step (Scheme 6 (19). The hydroxylamine 54 was obtained from 3,4-dimethoxybenzaldoxime (52) by reflux in carbon tetrachloride with ethylene glycol boronate 53 in 68% yield. Condensation of 54 with methyl 5-oxopentanoate (55) afforded the nitrone 56, which was directly subjected to cycloaddition in refluxing toluene to give a l-aza-7-oxanorbomane (57) in 50%... 

Dihydroxyhexanoic acid, 1,5-lactone, Y 5.5 3-Methyl-5-oxopentanoic acid, A"30.8 Rhamnal, C"1.6... 

Methyl-5-hepten-2-one is a constituent of lemongrass oil. How could you synthesize this substance from methyl 4-oxopentanoate ... 

Thus, the name of 1 is methyl 4-oxopentanoate and the name of 2 is 5-amino-2-pentanol. Further examples are shown ... 

The synthesis of 4-alkyl-y-butyrolactones 13 and 5-alkyl-<5-valerolactones 14 can be achieved in high enantiomeric excess by alkylation of ethyl 4-oxobutanoate and ethyl 5-oxopentanoate (11, n = 2, 3). The addition of diethylzinc, as well as dimethylzinc, leads to hydroxy esters 12 in high optical purity. When methyl esters instead of ethyl esters are used as substrates, the enantioselectivity of the addition reaction is somewhat lower. Alkaline hydrolysis of the hydroxy esters 12, followed by spontaneous cyclization upon acidification, leads to the corresponding y-butyro- and -valerolactones32. 

The matched double asymmetric reaction of the diastereomeric aldehyde methyl (2SAS)-2.4-dimethyl-5-oxopentanoate and (otS,S,S)-5 was performed under 4kbar pressure at room temperature giving 20 as the only observed isomer. 

The following substrates were obtained from commercial sources, methyl pyruvate (1), methyl acetoacetate (2), methyl 4-oxopentanoate (1), and methyl 3-oxopentanoate ( ). Alkyl 5-oxohexanoates (4, 5 and 6) were prepared by condensation of methyl acetoacetate and methyl acrylate followed by acidic hydrolysis, decarboxylation, and esterification [8]. Methyl 3-oxo-4-methylpentanoate... 

In a glass autoclave equipped with a magnetic stirrer bar were placed BisP -RuBr2 (52 mg), methyl 3-oxopentanoate (10.7 g), and degassed methanol/ water (10/1) 200 mL under an argon atmosphere. 

For example, 3-isopropyl-7a-methyl-5-oxo-perhydropyrrolo[2,l-A]oxazole 244 formed by condensation of (A)-vali-nol 243 and 2-(2,3-dimethoxy-5-methylphenyl)-4-oxopentanoic acid 242 in toluene was the key intermediate in the total synthesis of (-)-mastigophorene B 245 (Scheme 35) <1999JA2762>. 

This enzyme [EC 2.6.1.42], also referred to as transaminase B, catalyzes the reversible reaction of leucine with a-ketoglutarate (or, 2-oxoglutarate) to produce 4-methyl-2-oxopentanoate and glutamate. The pyridoxal-phosphate-dependent enzyme will also utilize isoleucine and valine as substrates. However, this enzyme is distinct from that of valine pyruvate aminotransferase [EC 2.6.1.66]. See also Leucine Aminotransferase... 

This enzyme complex [EC 1.2.4.4], also known as 3-methyl-2-oxobutanoate dehydrogenase (lipoamide) and 2-oxoisovalerate dehydrogenase, catalyzes the reaction of 3-methyl-2-oxobutanoate with lipoamide to produce S-(2-methylpropanoyl)dihydrolipoamide and carbon dioxide. Thiamin pyrophosphate is a required cofactor. The complex also can utilize (5)-3-methyl-2-oxopenta-noate and 4-methyl-2-oxopentanoate as substrates. The complex contains branched-cham a-keto acid decarboxylase, dihydrolipoyl acyltransferase, and dihydrolipoa-mide dehydrogenase [EC 1.8.1.4]. 

This enzyme [EC 1.4.1.12] catalyzes the reaction of 2,4-diaminopentanoate with NAD(P)+ and water to produce 2-amino-4-oxopentanoate, ammonia, and NAD(P)H. The enzyme can also utilize 2,5-diaminohexanoate as a substrate (although not as effectively as the substrate mentioned above) forming 2-amino-5-oxohexanoate, which then cyclizes nonenzymically to form 1-pyrroline-2-methyl-5-carboxylate. 

This enzyme [EC 1.1.1.85] catalyzes the reaction of 3-carboxy-2-hydroxy-4-methylpentanoate and NAD+ to produce 3-carboxy-4-methyl-2-oxopentanoate and NADH. The product then decarboxylates, generating 4-methyl-2-oxopentanoate. 

This pyridoxal-phosphate-dependent enzyme [EC 2.6.1.6] catalyzes the reversible reaction of leucine with a-ketoglutarate (or, 2-oxoglutarate) to produce 4-methyl-2-oxopentanoate and glutamate. See also... 

Three equivalents of the carbenoid (EtZnCHjI) are necessary for the dean formation of the product. One of the equivalents serves to fadlitate formation of the enolate, while a second equivalent provides the methylene group that is incorporated into the product. However, if the reaction is performed with only two equivalents, significant amounts of starting material and a second product, methyl 2,4,4-trimethyl-3-oxopentanoate, are generated in the reaction. 

Methyl 4,4-dimethyl-3-oxopentanoate was obtained from Lancaster Synthesis, Inc., and used without further purification. 

Methyl 4,4-dimethyl-3-oxopentanoate Pentanoic acid, 4,4-dimethyl-3-oxo-, methyl ester (9) (55107-14-7)... 

Other novel diazo compounds that have been subjected to 1,3-dipolar cycloaddition with activated alkenes, and that give unusually functionalized pyrazolines (Scheme 8.7), include l-diazo-3-trimethylsilylpropan-2-one (20) (49), 2-diazo-methyl-4(57/)-furanones (21) (50), methyl 2-diazo-5-methylanilino-5-oxopentano-ate (22) (51), 2-(acylamino)-2-diazoacetates (23) (51), ethyl 2-diazo-4,4,4-trichloro-3-(ethoxycarbonylamino)butyrate (24) (52), and diazopropyne (53). 

No metalation is required for the / -fluorination of a-oxo esters.150 Ethyl 3-methyl-2-oxo-butanoate and 3-methyl-2-oxopentanoic acid give the corresponding /f-fluoro derivatives 30 a and 30 b, respectively, in quantitative yield on reaction with A-fluorobis(trifluoromethylsul-fonyl)amine (Id). 3-Fluoro-2-oxobutanoic acid (30c) is exclusively formed by treating 2-oxobutanoic acid with an equimolar amount of reagent Id.150... 

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