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Synthesis 2004(2): 221-226  
DOI: 10.1055/s-2004-815917
PAPER
© Georg Thieme Verlag Stuttgart · New York

C 2-Symmetric Chiral Bis(thiazoline) and Bis(oxazoline) Ligands and their Application in the Catalytic Asymmetric Allylic Alkylation

Bin Fu, Da-Ming Du*, Qing Xia
Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
Fax: +86(10)62751708; e-Mail: dudm@pku.edu.cn;
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Publication History

Received 16 October 2003
Publication Date:
13 January 2004 (online)

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Abstract

A series of novel C 2-symmetric bis(thiazoline) ligands with dibenzo[a,c]cycloheptadiene backbone as the substituent on the thiazoline ring were synthesized using the simple reagent phosphorus pentasulfide, and their application in catalytic allylic alkylation was investigated by comparison with the corresponding bis(oxazolines). Palladium-bis(oxazoline) complexes furnished good enantioselectivity (up to 87% ee), while bis(thiazolines) only gave up to moderate enantioselectivity (56% ee) with CH2Cl2 as solvent. Preliminary explanation of the catalysis mechanism is given for the difference of two types of Pd(0)-ligand complexes.

Key words

bis(thiazolines) - bis(oxazolines) - synthesis - allylic alkylation - asymmetric catalysis

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Crystallographic data (excluding structure factors) for the structures in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary publication number CCDC-216676. Copies of the data can be obtained, free of charge, on application to CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK [fax: +44(1223)336033 or e-mail: deposit@ccdc.cam.ac.uk].