Both the cyclopentene ring and the cyclohexenone ring were oxidized next in an ozonolysis ( ozone ) forming triketone "'29 "', an aldol condensation of the 1, 5-dicarbonyl unit ( pyrrolidine acetate ) formed cyclohexene "'30 "'with tosylation of the oxime group, a second oxidation with periodic acid cleaves the cyclohexene ring and diazomethane esterifies the resulting carboxylic acid group in "'31 " '.
42.
In their full account of their 2000 Communication, the group revealed that proline together with the thiazolium salt " 5, 5-dimethyl thiazolidinium-4-carboxylate " were found to be the most effective catalysts among a large group of amines, while catalysis with ( S )-1-( 2-pyrrolidinylmethyl )-pyrrolidine salts formed the basis for the development of diamine organocatalysts that have proven effective in a wide variety or organocatalytic reactions.
