Studies concerning the design of chiral ligands based on the phosphetane structural motif are presented. Homochiral phosphetanes are easily accessible from the reactions of suitable olefins with chiral dichlorophosphines, which are readily prepared from chiral pool precursors such as menthol and pinene. Alternatively, C-chiral phosphetanes can be obtained from primary phosphines and derivatives of optically pure 1,3-diols.
The chemistry of 1-menthyl-2,2,3,3-tetramethyl-substituted phosphetane derivatives has been studied in some detail. The parent phosphetane oxide undergoes highly selective transformations which afford diastereomerically pure a-substituted phosphetanes. This flexible methodology allows significant modification of the phosphorus environment, the introduction of selected functional groups or additional chiral centers, and the formation of symmetrical and nonsymmetrical bidentate phosphines. Preliminary investigations of phosphetanes as ligands in enantioselective organometallic catalysis have been performed with P-chiral monodentate derivatives in various palladium-catalyzed reactions.