Cyclopentanecarboxaldehyde

The yield of recovered mercuric sulfate is 600-700 g. This material plus fresh mercuric sulfate to give 740 g. can be used in a subsequent preparation of cyclopentanecarboxaldehyde without affecting the yield. 

Cyclopentanecarboxyaldehyde may trimerize if heating is prolonged hence a fast, simple distillation is done. When the distillation residue is cooled, a solid may appear. This solid can be distilled above 78° (100 mm.) as a clear liquid which solidifies when allowed to stand. Recrystallization of this material from 95% ethanol gives a white solid melting at 122-124°. This product was shown to be cyclopentanecarboxaldehyde trimer by... 

Cyclopentanecarboxaldehyde has been prepared by the procedure described above 2 3 by the reaction of aqueous nitric acid and mercuric nitrate with cyclohexene 6 by the action of magnesium bromide etherate 6 or thoria 7 on cyclohexene oxide by the dehydration of frarei-l, 2-cyclohexanediol over alumina mixed with glass helices 8 by the dehydration of divinyl glycol over alumina followed by reduction 9 by the reaction of cyclopentene with a solution of [HFe(CO)4] under a carbon monoxide atmosphere 10 and by the reaction of cyclopentadiene with dicobalt octacarbonyl under a hydrogen and carbon monoxide atmosphere.11... 

This procedure uses readily available starting materials and in one operational step generally gives higher yields of cyclopentanecarboxaldehyde than other preparations described in the literature. Because mercuric sulfate is an expensive reactant, a method of regenerating the mercury products is given. Cyclopentanecarboxaldehyde is a useful intermediate for many cyclopentane derivatives. 

Certain preparations—mesitoic acid, 7-t-butoxynorbornadi-ene, cyclopentanecarboxaldehyde, t-butyl azidoformate, indole-... 

CYCLOOCTENE, 1-NITRO-, 50, 84 CYCLOPENTANECARBOXALDEHYDE, 1-PHENYL-, 51, 24 Cyclopentane-1,3-dione, 52, 4 Cyclopentanones, 54, 32 CYCLOPENTYLAMINE, 1-PHENYL-,... 

A suspension of thallium (III) nitrate in pentane at room temperature can react with alkenes to give vtc-dinitrate esters. Cyclohexene reacts with this reagent to give 1,2-cyclohexanediol dinitrate (85 %) (as a mixture of isomers) and 15 % cyclopentanecarboxaldehyde (hydride shift in the dethallation step). Some alkenes react extremely slowly with this reagent e.g. isomeric 5-decenes. 

A substituent at C-3 of a 2-amino-l,2-dideoxycyclitol in which the amino group is equatorial would also be removed in deamination. A simple model for this reaction is the conversion of a cis-trans mixture of 2-methoxycyclohexylamine into a mixture of products that included cyclopentanecarboxaldehyde.266 The latter presumably arose from the trans amine and from that proportion of the cis amine which... 

Oxidation of cyclohexene by peroxydisulfate in the presence of copper(II) salts results in the formation of cyclopentanecarboxaldehyde as the main product in an aqueous acetonitrile solution (equation 261), and 2-cyclohexenyl acetate in an acetic acid solution (equation 262).588,589 Reaction (261) has been interpreted as the formation of a radical cation (186) by oxidation of cyclohexene with S2Og, followed by hydrolysis of (186) to the /3-hydroxy alkyl radical (187), which is oxidized by copper(II) salts to the rearranged aldehydic product (188 equation 263).589... 

Cyclohexene is oxidized to cyclopentanecarboxaldehyde in 85% yield in fact this TTN-induced ring contraction is probably the method of choice for preparation of this aldehyde. This reaction was used by Corey and Ravindranathan- as one step in a synthesis of 11-desoxyprostaglandins for the conversion of (1) into (2). However, in this case, the use of the original conditions led to complex mixtures containing only a... 

Cyclopentanecarboxaldehyde, 493 Cyclopentanecarboxylic add, 494,495 Cydopentanone, 139, 214,445, 551 Cydopentene, 319 Cydopentene epoxide, 404 2-Cyclopentenone, 158, 227, 262, 511 2-Cyclopentenones, 218 Cyclopentenone thioketals, 218 1-Cyclopentenyl isobutyl ketone, 512 Cyclopentyne, 209 Cyclopropanation, 153 Cyclopropanecarboxaldehyde, 43,44, 520-521... 

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