2-Methylpropanoate ester

Unless the p keto ester can form a stable anion by deprotonation as m step 4 of Figure 21 1 the Claisen condensation product is present m only trace amounts at equi librium Ethyl 2 methylpropanoate for example does not give any of its condensation product under the customary conditions of the Claisen condensation... 

Other approaches to (36) make use of (37, R = CH ) and reaction with a tributylstannyl allene (60) or 3-siloxypentadiene (61). A chemicoen2ymatic synthesis for both thienamycia (2) and 1 -methyl analogues starts from the chiral monoester (38), derived by enzymatic hydrolysis of the dimethyl ester, and proceeding by way of the P-lactam (39, R = H or CH ) (62,63). (3)-Methyl-3-hydroxy-2-methylpropanoate [80657-57-4] (40), C H qO, has also been used as starting material for (36) (64), whereas 1,3-dipolar cycloaddition of a chiral nitrone with a crotonate ester affords the oxa2ohdine (41) which again can be converted to a suitable P-lactam precursor (65). 

Thus, sendarwine is systematically named as 6p-acetoxy-4,4a,5,6,7,8,8a,9-octahydro-3,4ap,5p-trimethyl-9-oxonaphtho[2,3-/)]furan-4p-yl-2-methylpropanoic acid ester. 

The next step yields 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester. L-proline tert-butyl ester (5.1 g) is dissolved in dichloromethane (40 ml) and the solution stirred and chilled in an ice bath. Dicyclohexylcarbodiimide (15 ml) is added followed immediately by a solution of 3-acetylthio-2-methylpropanoic acid (4.9 g) in dichloromethane (5 ml). After 15 minutes stirring in the ice bath and 16 hours at room temperature, the precipitate is filtered off and the filtrate is concentrated to dryness in vacuo. The residue is dissolved in ethyl acetate and washed neutral. The organic phase is dried over magnesium suifateand concentrated to dryness in vacuo. The residue 1-(3-acetylthio-2-methylpropanoyl)-L-proline tert-butyl ester is purified by column chromatography (silica gel-chloroform), yield 7.9 g. 

Chemical Name 2-(4-chlorophenoxy)-2-methylpropanoic acid ethyl ester Common Name Ethyl p-chlorophenoxylsobutyrate... 

Chemical Name 2-(4-(4-Chloroben2oyl)phenoxyl-2-methylpropanoic acid-1-methylethyl ester... 

RN 66195-31-1 MF CnH25N04 MW 307.39 EINECS 266-229-5 CN 2-methylpropanoic acid 4-[2-(methylamino)ethyl]-1,2-phenylene ester... 

C,2H 4C104 31637-96-4) see Etofibrate 2-(4>chlorophenoxy)-2-methylpropanoic acid 3-hydroxy-propyl ester... 

Phenyl 2-methylpropanoate Propanoic acid, 2-methyl-, phenyl ester (20279-29-2), 75, 116... 

Representatives of the subfamilies Omaliinae and Proteininae (omaliine group) possess an abdominal defensive gland reservoir that opens out between sternite 7 and 8 [ 120]. The multi-component mixtures contained in these glands are used for defence. In Omaliinae and Proteininae the secretion is characterized by mixtures of acids (e.g. 2-methylpropanoic acid, hexanoic acid, 2-octenoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, butyric acid, and tiglic acid), aldehydes (( )-2-hexenal, heptanal, octanal, nonanal), ketoaldehydes such as 4-oxo-2-hexenal 41 (Scheme 5), 6-methyl-5-hepten-2-one, alcohols (octanol, ( )-2-hexen-l-ol, 2-methylbutan-l-ol), alkanes (nonadecane), esters (2-methylbutyl tiglate 42, various propanoates, 2-hexenyl 3-methylbutanoate, 2-methylbutyl 2-methylbutanoate, octanoates,butanoates), and aromatic compounds (e.g. 2-phenethyl 3-methylbutanoate 43). Unusual compounds are 2-... 

The procedure is successful with ketene silyl acetals prepared from the enolate anions of methyl 2-methylpropanoate and methylpropanoate, and provides good yields of the propionic esters 7 in a single step (Scheme 10.20). The latter are known to be intermediates in the preparation of analgesic compounds. No significant difference in the yields is observed when 4-chloroaniline is used as the starting material in place of its dimethylated analogue [31]. 

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