Tricyclo deca-3,7-diene-9,10-dicarboxylic

Dimethyl tricyclo[4.2.2.02 -5]deca-3,7-diene-9,10-dicarboxylate adds bromine and iodine only to the less hindered double bond to give the syn 1,2-addition product of the cyclobutene moiety79. The product composition from this compound depends on the temperature and the solvent. At high temperatures, the 1,2-addition predominates over the transannular reaction, but this predominance is small in a solvent like chloroform and is lost in a protic solvent such as acetic acid (equation 47). 

The syntheses of mono- and dicarboxylic acids via ionic reaction steps starting from butadiene and carbon dioxide are well studied reactions. For instance, Cg-, C13- and C-]7-monocarboxylic acids as well as Ciq-dicarboxylic acids can be prepared in the presence of sodium [72,73]. Also metal phenolates catalyze the synthesis of acyclic dicarboxylic acids. When sodium phenolate is dissolved in dimethylformamide and CO2 and butadiene are added and reacted 3 hrs at 50 C, muconic acid is formed in 81 % yield. Hydrogenation of muconic acid leads to adipic acid [741. In a similar reaction, Thiele s acid, that is tricyclo-[5.2.1.02 6]deca-3.8-diene-4.9-dicarboxylic acid, is formed by two moles of cyclopentadiene and two moles of carbon dioxide [79 (Equation 13). 

Ci2Hio02f 1,6-Methano-cyclodecapentaene-2-carboxylic acid, 30B, 117 Cl2H10O3, anti-Tricyclo[4.2.2.0 ]deca-3,9-diene-7,8-endo-dicarboxylic anhydride, 39B, 138... 

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