On the carbocyclization of ω-styrenylbenzyllithiums

ω-Styrenylbenzyllithiums readily available from the corresponding ω-styrenylbenzyl selenides and butyllithiums provide after methanolysis 1-aryl-2-benzyl cyclopentanes with very high stereocontrol. The compound bearing these two groups in trans-position is produced, when the reaction is carried out in THF at -78°C or in ether at -100°C whereas its stereoisomer is generated if the reaction is performed in ether at 0°C. We proved that these reactions occur under kinetic control.