Cyclopentanones references

A variety of esters can be prepared from the corresponding ketones usiag peracids ia a process usually referred to as the Baeyer-Villiger reaction (95) ie, cyclopentanone is converted to 5-valerolactone upon treatment of the ketone with peroxytrifluoroacetic acid ... 

The formation of crystal inclusion of 47 and 48 with cyclic ketones of suitable ring size (cyclopentanone, cyclohexanone) and with cyclohexene oxide are also important facts. Corresponding inclusion compounds with alcohols or amines could not be obtained. With reference to the heterocyclic guest molecules, the suitability of the ring size is likely to be the decisive factor for guest inclusion. 

Other unsaturated ketones also react with enamines to yield dihydropyrans e.g. enamines derived from cyclopentanone add 2-benzylidenecyclohexanone to give 188 (equation 80)101. For a critical discussion of these reactions, see Reference 2, p. 3401. 

The following summary can now be made with reference to the energy diagrams (Figure 4). Cyclopentanone (17,47,48) f... 

Another interesting contrast is afforded by the rarity of ring expansion of cyclopentanones. 2,2,5,5-tetramethylcyclopentanone [101], for example, shows no tendency to undergo ring expansion in methanol (15). A few examples of ring expansion for cyclopentanones are known in polycyclic systems [for an exception, see reference (25)] (9). 

The chemistry of synthetic jasmine materials was given an enormous boost in the 1930s when Nylon 66 was launched as a product. Nylon 66 is a polyamide prepared using adipoyl chloride and hexamethylenetetramine as monomers. The 66 in the name refers to the fact that there are 6 carbons in each type of unit that lies between the amide links in the polymer chain. Thus, adipic acid is the key feedstock for Nylon 66 and the introduction of the latter meant that the former became a basic chemical commodity. Pyrolysis of the calcium or barium salt of adipic acid produces cyclopentanone, and so the availability of large quantities of the acid meant that the ketone could also be prepared at low cost. 

Treatment of (124) with 0.1 equiv. of SnCU for <15 min at 0 C gives ene adduct (125) in 85% yield as an 80 20 cis. trans mixture.85 On the other hand, treatment of (126) with 2.9 equiv. of BF3-Et20 for 1 h at 25 C gives cyclopentanone (127 Scheme 20).86 Examination of the reactions of (126) with various al-kylaluminum halides indicates that the nature of the reaction can be controlled by variation of the strength and amount of Lewis acid.76 Treatment of (126) with 1 equiv. of Me2AlCI at -78 °C gives primarily (128) as a 4 1 mixture of a-methyl and p-methyl isomers. (In the text (126)- 134) refer to the alcohol or carbonyl compound obtained after workup). Alcohol (128) is probably formed by a concerted ene reaction or a n-complex rather than a zwitterionic intermediate, since concerted thermal ene reactions of 1,6-dienes give mainly m-substituted cyclopentanes.5... 

In connection with prostaglandin syntheses, Michael additions to cyclopentanones with exo- and endocyclic double bonds have been intensively explored. In all cases protonation of the intermediate occurs in such a way that the side chains end up in the tram position, as exemplified by the following76,78-79 (see also references 77 and 80-83). 

Scheme 7. Examples for Enantiomer Separations by Crystallization with TADDOLs. Besides the original TADDOL (from tartrate acetonide and PhMgX), Toda et al. [44] have often used the cyclopentanone- and cyclohexanone-derived analogs. The dynamic resolution (resolution with in-situ recychng) of 2-(2-methoxyethyl)cyclohexanone was reported by Tsunoda et al. The resolved compounds shown here are only a small selection from a large number of successful resolutions, which include alcohols, ethers, oxiranes, ketones, esters, lactones, anhydrides, imides, amines, aziridines, cyanohydrins, and sulfoxides. The yields given refer to the amount of guest compound isolated in the procedure given. Since we are not dealing with reactions (for which we use % es to indicate enantioselectivity with which the major enantiomer is formed), we use % ep (enantiomeric purity of the enantiomer isolated from the inclusion...

By chromophore-polymer composite materials, we refer to chromophores physically incorporated (dissolved) into commercially available polymer materials such as amorphous polycarbonate (APC) [58] finm Aldrich Chemicals. Chromophore and polymer are dissolved in a suitable spin-casting solvent, such as cyclopentanone. Spin-cast thin films are heated to near the glass transition temperature of the composite material (which will vary with chromophore concentration due to the plasticizing effect of the chromophore). Acentric chromophore order is induced by electric field poling. If one assumes that the presence of the polymer host does not stericaUy hinder the reorientation of the chromophores under the influence of the poling field, the order parameter can be readily calculated. We have already noted that if chromo-phore-chromophore intermolecular electrostatic interactions are neglected then (cos d) = fiF/5kT and the order parameter will be independent of chromophore concentration (or number density, N). Intermolecular electrostatic interactions can be treated at several levels of sophistication. 

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