الفهرس | Only 14 pages are availabe for public view |
Abstract The aim of my work is to design new and efficient synthetic methodologies of chiral heterocycles bearing multiple or quaternary chiral centers under spiro chiral ligand-Pd(II) complex catalysis. Part 1: The first diastereoselective and enantioselective domino cyclization/cycloaddition reactions of alkenyl oximes were established using a Pd(II)-(R)-Tol-SDP complex and triflic acid. The present process gave polycyclic heterocycles with four chiral stereogenic centers in almost quantitative yields and high stereoselectivities (up to 70% ee, exo/endo = 97/3). The protonolysis of the Pd-C bond of the palladium intermediate II / III was the key step in this transformation. Triflic acid was the best candidate to cleave this bond affording the corresponding nitrone intermediate IV. The role of triflic acid was supported by the detection of deuterated nitrone intermediate d-IV via ESI-MS analysis. |