Penta cyclopentadiene

One method of producing penta(methoxycarbonyl)cyclopentadiene radical is by irradiation of [SnBu3(OH2)2]+[C5(C02Me)5]" (reaction 36)58. The radical thus produced is remarkably stable, with the ESR signal not decreasing in intensity one hour after cessation of photolysis. 

Migrations of arylazo groups were first detected in the l,2,3,4,5-penta(methoxycarbonyl) cyclopentadiene 259 (equation 89)119-122. The randomization mechanism was considered as most probable because the reaction rate increases with increase in the solvent polarity (AGf9S = 56.9 to 69.1 kJmol-1). 

When cyclic 1,3-dienes were employed, the reactions were found to be exo selective [Eq. (28)]. In contrast, the Diels-Alder reactions of free thio-and selenoaldehydes with cyclopentadiene occur with a preference for the endo isomer.235 Thus, coordination of thio- and selenoaldehydes to a penta-carbonylmetal fragment resulted in a reversal of the endo selectivity. The exo/endo product ratio of [W(CO)5 E = C(Ph)H ] was 7.3 1 (E = S) and 2.6 1 (E = Se), whereas the kinetically controlled exo/endo ratio of the cycloadducts obtained by trapping of the free heterobenzaldehyde with cyclopentadiene was reported to be 1 7236 and 1 4235 237 (E = S) and 1 2.6238 and 1 4239 (E = Se), respectively. 

Chloro-(i/4-cyclopentadien)-(penta-fluoro-phenvl)- ElOb,. 426 (Cl - C6F5)... 

Chlordane is a mixture of at least 120 compounds and technical chlordane typically contains 64-67% chlorine (Dearth Hites, 1991a,b WHO, 1995). Of these 120 compounds, 60-75% are chlordane isomers (cis- and irons- ) and the remainder is related to endo-compounds that include heptachlor, nonachlor, diels-alder adduct of cyclopentadiene and penta/hexa/octachlorocyclopentadienes (UNEP Chemicals, 2002). Heptachlor contributes up to 10% of technical chlordane and it is also a pesticide formulation. 

Scheme 10. Reaction sequence for the synthesis of tri-, tetra-, and penta(isopropyl)cyclo-pentadienes (34,35) from di(isopropyl)-Cp (59) via a series of metallations/alkylations. Tri(isopropyl)-Cp is obtained in a 4 1 mixture of the 1,2,4- and 1,2,3-substituted isomers. The C—H acidic tetra(isopropyl) isomers are separated from the 5,5 -geminal dialkylated forms by their transformation in the sodium salt and evaporation of the nonmetallated components. Subsequent hydrolysis yields l,2,3,4-tetra(isopropyl)cyclopentadiene in an iso-merically pure form. Similarly, l,2,3,4,5-penta(isopropyl)-Cp is purified after separation of the 1,2,3,S,5 derivative as the main alkylation product. For more details and the respective yields, see Refs. 34 and 35.

Lidov A process for chlorinating cyclopentadiene to octachloropentadiene, which is then thermally dechlorinated to hexachlorocyclopentadiene (HCCP), used as an intermediate in the manufacture of insecticides and flame retardants. The initial chlorination is catalyzed by phosphorus penta-chloride or arsenious oxide. Invented by R.E. Lidov in the Netherlands and commercialized by the Shell Chemical Company. 

The Diels-Alder reaction between cyclopentadiene and acryloyloxazolidinone is enantioselectively catalysed by the bis(oxazoline)-magnesiuni perchlorate complex. " Ab initio calculations of the ionic Diels-Alder reactions of triazoloisoquinolinium and tetraniethoxycarbonylqijinoliziniijin ions with electron-rich dienophiles have been reported. The 2 - -4-cycloadditions of arenediazonium ions with ( )-penta-1,3-diene, 2,3-dimethylbutadiene, and ( )-2-methylpenta-l,3-diene produce dihydropyr-idazines and pyridazinium salts. The similarity approach has been applied to predict successfully the preferred regiochemistry of various types of pericyclic reaction including polar and semi-polar Diels-Alder and 2 - - 2-cycloadditions. ... 

Scheme 2.38 Acidities of cyclopentandiene, pentafluorocyclopentadiene [90], and penta-kis(trifluoromethyl)cyclopentadiene [91].

CgHu, Cyclooctene, iridium complex, 21 102 C10H4, Benzene, l-isopropyl-4-methyl-, ruthenium complex, 21 75 CioHit, 1,3-Cyclopentadiene, 1,2,3,4,5-penta-methyl-, 21 181... 

The cycloaddition of simple alcohols, acrylates la-d with cyclopentadiene (2)7 and 1,3-penta-diene (7 piperylene)8 succeeds only with moderate optical yields. 

Also, a synthesis of azulene that gives good yields starts from the fulvene derivative860 that is formed quantitatively from cyclopentadiene and penta-nedial A-methyl-A-phenylmonoimide ... 

Diels-Alder adduct of cyclopentadiene and penta-chlorocyclopentadiene, 1% hexachloro-cyclopentadiene, 1% octachlorocyclopentene, and 15.5% miscellaneous constituents. Oxy-chlordane and heptachlor epoxide are toxi-cologically significant degradation products (Figure 7.1). 

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