Metal template synthesis and coordination chemistry of functionalized P-chiral phosphanorbornenes

The organopalladium complex containing the (S)-form of ortho-palladated (1- (dimethylamino)ethyl)-naphthylalene has been used successfully as the chira l template to promote the asymmetric cycloaddition reactions between coordi nated 3,4-dimethyl-1-phenylphosphole and two dienophiles: N,N-dimethylacryl amide and styrene. The mechanism, the rate and the stereoselectivity of the se chiral template promoted reactions are affected by the number of coordin ation sites available on the palladium template and the coordination potent ial of the dienophiles. At room temperature, the intramolecular cycloadditi on reaction with N,N-dimethylacrylamide gave the corresponding P-chiral (-) -(S-P)-exo-amidophosphanorbornene stereospecifically in 3 d. Under similar conditions, the corresponding intermolecular process gave a pair of separab le diastereomeric endo-substituted amidophosphanorbornene complexes in 32 d . With styrene, the intermolecular cycloaddition reaction at 80 degrees C g ave a pair of diastereomeric endo-substituted phenylphosphanorbornene compl exes in 3 d. No exo-cycloaddition reaction occurred when styrene was used a s the dienophile. The first optically active and stable amido-O bonded plat inum complex (R-P,R-P)-[Pt(exo-amidophosphanorbornene-P,O)(2)](ClO4)(2) and its palladium analogue have been isolated and characterized by P-31 NMR sp ectroscopy and X-ray crystallography. (C) 1999 Elsevier Science Ltd. All ri ghts reserved.