1.3- Cyclopentadiene reaction with hydrogen chloride

The reactions are very fast, and halide ion addition always leads to 77-allylpalladium halide dimers. The cyclopentadienyl moiety has been isolated in the form of cyclopentadiene (reaction with hydrogen chloride), or as a carboxylic acid dimer (reaction with BuLi -f CO2). That part of the attacking reagent bearing positive charge always combines with the C5H5... 

Cyclopenteaediol isomers have previously been prepared by hydrolysis of acetates produced by reaction of dibromocyclopen-tene with potassiiun acetate in acetic acid by reaction of cyclo-pentene with selenium dioxide in acetic anhydride or by reaction of cyclopentadiene with phenyl iodosoacetate/ with lead tetraacetate, or with peracetic acid in the absence of base. Preparation of cydopentenediol without intermediate formation of acetates has been accomplished by reaction of cyclopentadiene with hydrogen peroxide in the presence of osmium tetroxide in terf-butanol, and hy reaction of cyclopentadiene with peracetic acid in a methylene chloride suspension of anhydrous sodium carbonate, followed by hydrolysis of the resulting epoxycyclo-pentene. ... 

Reports of studies on the reactions of diphosphenes have begun to appear. Like (137), (140) is stable towards methanol but is cleaved by hydrogen chloride. The less hindered (143) dimerizes at room temperature in a few hours, and gives cycloaddition products with Sg and cyclopentadiene (Scheme 11). Oxidation... 

Electrophilic addition is the characteristic reaction of alkenes, and conjugated dienes undergo addition with the same electrophiles that react with alkenes, and by similar mechanisms. Hydrogen chloride, for example, adds to the diene unit of 1,3-cyclopentadiene to give 3-chlorocyclopentene. Mechanism 10.3 is analogous to the electrophilic addition of HCl to alkenes. 

Halides and other salts as well as metal carbonyls sometimes react with cyclopentadiene to afford cyclopentadienyl complexes with concomitant evolution of hydrogen, hydrogen chloride, or other reduction products, such as CjHg. These reactions take place under relatively severe conditions at high temperatures and often under elevated pressures ... 

Ruthenocene is easily synthesized by the reaction of ruthenium chloride with cyclopentadiene as shown in Scheme 16.1. Ruthenocene is a cream-colored crystal of mp 199-201 °C, stable similar to ferrocene, and it decomposed at ca. 610 C. It is heated at 600 °C under hydrogen atmosphere to yield highly pure filmy ruthenium metal. It is stable to chlorine, hydrogen chloride and sulfuric acid in the absence of oxygen [17]. 

Schreiner et al. developed thiourea catalyst as a promising hydrogen donor, which has more benefit in solubility, synthesis and catalytic mrn over number compared with urea catalyst, in the Diels-Alder reaction of A-crotonyloxazolidinone and cyclopentadiene [22,23] (Table 9.7). A,A -Di[3,5-bis(trifluoromethyl)phenyl]thiourea accelerates the reaction and improves stereoselectivity (run 4) similar to a metal catalyst such as aluminium chloride (AICI3) (mn 2) or titanium chloride (TiCls) (run 3). 

The impact of acidic and basic ionic liquid melts (l-ethyl-3-methylimidazolium chloride) on the rates of the Diels-Alder reaction between cyclopentadiene and methylacrylate has been investigated with the PDDG/PM3 method for the QM part and the OPLS force field for the solvent molecules. The ability of the ionic liquid to act as hydrogen bond donor (cation effect), moderated by its hydrogen bond... 

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