Trans-2-Phenylcyclopropanecarboxylic acid

The checkers note that in the paper by Inouye, et al. the diacid was prepared by ozonolysis of (+)-trans-2-phenylcyclopropanecarboxylic acid having 96.3% optical purity. The product diacid was purified by sublimation and recrystallization from water to obtain material giving the cited physical properties. Although the original publication claims an optical purity of 96.3% for this diacid, it is probably optically pure because of the recrystallization step. 

Since (Z)- and ( )-stereoisomers of unsaturated oxazolones can be obtained using appropriate isomerization procedures, cis and trans isomers of cyclopropane derivatives can be obtained in a stereoselective manner, although special care must be taken with experimental conditions to obtain the best stereoselectivity. Both racemic cis- and fraui-l-amino-2-phenylcyclopropanecarboxylic acid 641 and 644 have been obtained from the corresponding (Z)- or ( )-4-benzylidene-2-phenyl-5(4//)-oxazolone 621 and 642 using diazomethane. Care was taken to affect the... 

A solution of the above ester (207.8 grams) and 64.5 grams of sodium hydroxide in 80 cc of water and 600 cc of ethanol is refluxed for 9 hours. The carboxylic acid of 2-phenylcyclopropane is liberated with 200 cc of concentrated hydrochloric acid. The 2-phenylcyclopropanecarboxylic acid contains 3 to 4 parts of the trans isomer to 1 part of the cis isomer. The acid is recrystallized from hot water. The pure trans isomer comes out as crystalline material (solid) while the cis isomer stays in solution. 

Curtius reaction. The overall process of converting an acid through the azide and isocyanate into an amine is known as the Curtius reaction. For application of the Curtius reaction to Cii-2-phenylcyclopropanecarboxylic acid, J. Weinstock found the route to the azide through the acid chloride unsatisfactory because of ready isomerization to the trans acid chloride. An efficient alternative method utilizes a mixed anhydride intermediate of a type found serviceable in the synthesis of peptides. A solution of the acid in aqueous acetone was treated with triethylamine to... 

Both trans- and c/j-2-phenylcyclopropanecarboxylic acid (6) can also be decarboxylated with lead tetraacetate in benzene at 80 C in the presence of a catalytic amount of pyridine and copper(II) acetate to give rran. -l,2-diphenylcyclopropane (8) in low yield (18-22%). When the oxidative decarboxylation of these carboxylic acids is carried out with lead tetraacetate in the presenee of iodine under irradiation ra ,v-l-iodo-2-phenylcyclopropane (9) is obtained as the sole product in 43% yield. Under identical conditions 2,2-diphenylcyclopropanecarboxylic acid leads to 2-iodo-l,l-diphenylcyclopropane (mp 45.5 C) in 57% yield. 

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