Facial Selectivity in the Addition of Lithium Dimethylcuprate to 6-Substituted Tricyclo[5.2.1.02,6]deca-4,8-dienones. Synthesis of β-Substituted Cyclopentenones Using Flash Vacuum Thermolysis

Abstract

The stereoselectivity of the nucleophilic addition of lithium dimethylcuprate and lithium di-n-pentylcuprate to 6-substituted tricyclo[5.2.1.02,6]deca-4,8-dienones was investigated. It was shown that substituents at the 6-position can either exert a steric effect or an electronic effect. Steric approach control predominantly giving the endo product was observed for 6-alkyl substituents. Stereoelectronic control could be adequately rationalised using the Cieplak model. Flash vacuum thermolysis was used to prepare a series of β-substituted cyclopentenoids. The sequence leading to cyclopentenoids has an attractive scope.