Palladium catalysed enantioselective asymmetric allylic alkylations using the Berens’ DIOP analogue |
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Institution: | Departamento de Química and Centro de Química de Évora, Universidade de Évora, Rua Romão Romalho 59, 7000 Évora, Portugal |
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Abstract: | Berens’ DIOP analogue 1a was evaluated in a series of Pd(0) catalysed asymmetric allylic alkylations of both acyclic and cyclic substrates using both C- and N-nucleophiles. The reaction conditions were exhaustively analysed and a maximum ee of 60% was obtained using rac-1,3-diphenylpropenyl acetate 3 and malonate as the nucleophile. rac-3-Acetoxycyclohexene 5 gave inferior ee’s. Various solvents were applied including bmim]PF6. The results using benzylamine were comparable to those obtained using malonate. For 3, in all cases the reaction exclusively gave the branched alkylated product 4 and allylic amine 8, with no trace of their linear regioisomers. The allylPd-1a]BF4 complex 7 was prepared, characterised and screened in the asymmetric allylic alkylation of rac-1,3-diphenylpropenyl acetate 3. It was also immobilised on montmorillonite K-10 support and preliminary solid phase reactions were conducted with 3. |
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