Cyclopentenes ozone

Scheme 5 details the synthesis of / -cormorsterone (14) from 17. Oxidative scission of both carbon-carbon double bonds in 17 with ozone, followed by two straightforward operations, furnishes intermediate 38. The stability of the oxime in these systems is noteworthy, and is attributed to its hindered nature. At this juncture, it is instructive to note that substituted cyclopentene rings, like the... 

The polymer, (CsHB04)x, was prepd (together with some monomer) on passing ozone thru a chloro formic so in of cyclopentene. It Is a cryst compd, insol in org solvents reacts violently with coned sulfuric acid a powerful expl Reft 1) Beil 5, (30) 2) C.D. Harries H. 

Bennet, P.J., Harris, S.J., Kerr, J. A. (1987) A reinvestigation of the rate constants for the reactions of ozone with cyclopentene and cyclohexene under atmospheric conditions. Int. J. Chem. Kinet. 19, 609-614. 

Chemical/Physical. Gaseous products formed from the reaction of cyclopentene with ozone were (% yield) formic acid (11), carbon monoxide (35), carbon dioxide (42), ethylene (12), formaldehyde (13), and butanal (11). Particulate products identified include succinic acid, glutaraldehyde, 5-oxopentanoic acid, and glutaric acid (Hatakeyama et al., 1987). 

Surprisingly, the G3 fraction (Figure 11) shows almost the complete opposite behavior. The phenol peak becomes predominant, and this change is expressed in Figure 12, where the relative surface areas (response) of three typical fragments (base peaks for pyrrole, phenol, and 2-cyclopenten-l-one) are shown for line I. Similar results were obtained for line II (ozonation 5 mg/L for 10 min) where a high carboxylic content was also found (Figure 13). 

The synthesis of prostaglandin PGB1 as described by Morin et al. (Eli Lily Research Labs.), starts with 7-(2-methoxyphenyl)heptanoic acid 142 which is converted into 143 through Birch reduction, esterification and acetalization. Ozone cleavage of 143 and cyclization of the resulting dialdehyde affords cyclopentene carbaldehyde 144 which was subjected to ( )-selective Wittig olefination with... 

Cyclopentene-oxo-ozonides. A monomer, CsHgOa, was prepd (Ref 2) by the ozonization of cyclo-pentene dissolved in CCI4. It is a yel, volatile liq with a penetrating odor sol in chlf, ethyl acetate and acetic acid is decompd explosively by coned sulfuric acid explds on heating... 

Room temperature rate constants and Arrhenius parameters for the gas-phase reactions of ozone with cw-2-butene, 2-methyl-2-butene and a number of cycloalkenes are shown in Table 1 together with the literature values. The rate coefficients for cw-2-butene and 2-methyl-2-butene are in excellent agreement with the data evaluation of Atkinson and Carter [3]. The reported room temperature rate constants for the reaction of ozone with cyclopentene and cyclohexene show a considerable degree of scatter. The present results for cyclopentene provide support for the recent determinations by Bennett et al [24], Nolting et al [25], and Green and Atkinson [21], while the value for cycloheptene is slightly lower than the reported values [20] and [25]. No previous kinetic studies have been carried out on the reactions of O3 with cw-cyclooctene and cw-cyclodecene. 

Rate constants for the reaction of O3 with a number of substituted cycloalkenes were also determined in this work. From the results, the magnitude of the rate constant depends on the nature of the substituent and its position on the ring. As expected, substitution of a hydrogen atom attached at the 1 position in cyclopentene by an electron-withdrawing chlorine atom decreases the reactivity for reaction with the electrophilic ozone molecule. This would appear to be due to both a decrease in the pre-exponential factor and an increase in activation energy. 

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