Mechanismus der Cyclotrimerisierung von Phenylvinylketonen und die Kristallstrukturen von 1-((1R*,2S*,3R*,5S*)-und 1-((1R*,2S*,3R*,5R*)- 3.5-Dibenzoyl-2-hydroxy-2-phenylcyclohexylmethyl)-pyrrolidin-2-on/The Mechanism of Cyclotrimerisation of Phenylvinylketones and theCrystal Structures of 1-((1R*,2S*,3R*,5S*)-and1-((1R*,2S*,3R*,5R*)-3.5-Dibenzoyl-2-hydroxy-2-phenylcyclohexylmethyl)-pyrrolidin-2-on