Cyclopentanecarboxylic acid esters

The short Sanofi route to irbesartan (3) is outlined in Scheme 9.6. Dihydroimidazolone 27, which is prepared from the reaction of 1-amino-cyclopentanecarboxylic acid ester (25) with ethyl pentanimidate (26) in the presence of acetic acid in refluxing xylene, is alkylated with biphenylbenzyl bromide 18 in the presence of sodium hydride in DMF to give 28. Finally, the synthesis of irbesartan (3) is completed by the tetrazole formation from reaction of the nitrile group of 28 with tributyltin azide in refluxing xylene. [See Bernhart et al. (1993a, b).]... 

Problem 17.16 Synthesize cyclopentanecarboxylic acid from malonic ester. ... 

CONJUGATE ADDITION/CYCLIZATION OF A CYANOCUPRATE 2-CARB0METH0XY-3-VINYLCYCL0PENTAN0NE (Cyclopentanecarboxylic acid, 2-ethenyl-5-oxo-, methyl ester)... 

The methyl ester has also been obtained by esterification of cyclopentanecarboxylic acid.8 The acid, in turn, has been prepared by the Favorskii rearrangement,6 7 9-11 by the reaction of cyclopentyl Grignard reagent with carbon dioxide,12 by the carbonylation of cyclopentyl alcohol with nickel carbonyl13 or with formic acid in the presence of sulfuric acid,14 and by the hydrogenation of cyclopentene-1-carboxylic acid prepared from ethyl cyclopentanone-2-carboxylate 15 or from cyclopentanone cyanohydrin.16... 

Cyclohexylmethylpropiolaldehyde diethyl acetal, 39, 60 1,2-Cyclononanedione, 36, 78 Cyclopentadiene, 32, 41 36, 32, 35 Cyclopentanecarboxylic acid, METHYL ESTER, 39, 37 Cyclopentanol, 2-chloro-, irans-,... 

When one attempts E2 reactions with a-halo ketones using strong bases such as alkoxides, an interesting rearrangement pathway may occur called the Favorskii rearrangement. In this reaction, the a-halo ketone is converted to an ester. For example, 2-chlorocyclohexanone is converted to the methyl ester of cyclopentanecarboxylic acid by treatment with sodium methoxide in ether ... 

Chemical Name Cyclopentanecarboxylic acid, 1-phenyl-, 2-(2-(diethylamino)ethoxy)ethyl ester, citrate (1 1)... 

The rearrangement of cyclic ketones involves ring contraction. Thus, 2-chlorocyclobutanone (2.29) on treatment with sodium methoxide followed by hydrolysis is converted into cy-clopropanecarboxylic acid (2.30). In a similar manner, 2-bromocyclohexanone (2.31) on treatment with sodium methoxide gives methyl ester of cyclopentanecarboxylic acid (2.32). 

The malonic ester synthesis can also be used to prepare cvc/ualkane-carboxylic acids. For example, wlien 1,4-dibromobutane is treated with diethyl malonate in the presence of 2 equivalents of sodium ethoxide base, the second alkylation step occurs intnimolcailarly to yield a cyclic product. Hydrolysis and decarboxylation then give cyclopentanecarboxylic acid. I hree-, four-, five-,... 

Chiral Auxiliary. (/ ,/ )-( ) has been used as a chiral auxiliary to direct the stereochemistry of addition of a nucleophile to an acrylate moiety. Almost complete stereoselectivity is achieved in the addition of cyclopentanecarboxylic acid lithium dianion to the a-substituted acrylate substrate (eq 14). This methodology allows stereochemical control at the a-position of a p-amino ester and thus complements the methodology described above for the stereoselective formation of p-substituted p-amino esters. 

Oxobutyl)cyclopentanone-2-carboxylic acid ethyl ester Cyclopentanecarboxylic acid, 2-oxo-1-(3-oxobutyl)-, ethyl ester (10) (61771-81-1)... 

Table 4.8 Cinchona alkaloids and their derivatives promoted the enantioselective fluorination of 2-oxo-cyclopentanecarboxylic acid tert-butyl ester.

Cyc/o/ SPS. See Cetyl esters Cycloleucine 2714, Cycloleucine Cycloleucine. See 1-Amino-1-cyclopentanecarboxylic acid Cyclolube 62, Cyclolube 85] Cyclolub 120] Cyclolube 132] Cyclolube 210] Cyclolube 213] Cyclolube 270, Cyclolube 413] Cyclolube 2290] Cyclolube 2310] Cyclolube 4053] Cyclolube NN-1] Cyclolube NN-2. See Naphthenic oil Cyclomaltoheptaose Cyclomaltohexaose Cyclomaltooctaose. See Cyclodextrin Cyclomethicone... 

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