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Synfacts 2005(0): 0084-0084  
DOI: 10.1055/s-2005-869888
Polymer-Supported Synthesis
© Georg Thieme Verlag Stuttgart · New York

Evans’ Asymmetric Alkylation on Solid Supports

Contributor(s): Yasuhiro Uozumi, Tomohiko Beppu
T. Kotake, Y. Hayashi*, S. Rajesh, Y. Mukai, Y. Takiguchi, T. Kimura, Y. Kiso *
Kyoto Pharmaceutical University, Japan
Design and Synthesis of a New Polymer-Supported Evans-type Oxazolidinone: an Efficient Chiral Auxiliary in the Solid-Phase Asymmetric Alkylation Reactions
Tetrahedron  2005,  61:  3819-3933  
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Publication History

Publication Date:
20 July 2005 (online)

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Key words

Evans’ oxazolidinone - chiral auxiliaries - asymmetric synthesis - solid-phase organic synthesis - solid-phase asymmetric alkylation - recovery - recycling

Significance

Highly stereoselective solid-phase asymmetric alkylation reactions were achieved by using Evans-type oxazolidinone 1 as a chiral auxiliary. Benzylation at the α-position of propionic acid (R1 = CH3) gave 2-methyl-3-phenylpropionic acid in 70% yield with 97% ee in three steps. The resin-supported chiral auxiliary 1 was recovered by simple filtration and was reused three times without any loss of stereoselectivity (1st to 4th 96% ee, R1 = Bn, R2 = allyl).

Comment

Solid-phase Evans’ asymmetric alkylation reactions were achieved with enantioselectivities that were comparable to the solution-phase alkylation. The selectivity obtained with the immobilized chiral oxazolidinone 1 represents an improvement over the similar auxiliaries so far reported anchoring at the 4-position.

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