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Synthesis 2009(15): 2634-2645  
DOI: 10.1055/s-0029-1216880
FEATUREARTICLE
© Georg Thieme Verlag Stuttgart ˙ New York

Stereoselective Olefination Reactions Promoted by Rieke Manganese

José M. Concellón*, Humberto Rodríguez-Solla, Vicente del Amo, Pamela Díaz
Dpto. Química Orgánica e Inorgánica, Universidad de Oviedo, C/ Julián Clavería, 8, 33071 Oviedo, Spain
Fax: +34(985)103448; e-Mail: jmcg@uniovi.es;
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Publication History

Received 13 May 2009
Publication Date:
29 June 2009 (online)

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Abstract

A study of the advantages of using manganese, an inexpensive and nontoxic metal, to perform stereoselective β-elimination reactions and to promote sequential olefination reactions of aldehydes to obtain α,β-unsaturated esters and amides is presented. Various elimination reactions, all of them characterized by occurring with complete stereoselectivity and in high yields, were performed using active manganese (Mn*) as metalating agent. This ability of manganese has been applied to develop a novel and direct synthesis of (E)-α,β-unsaturated esters or amides and (Z)-α,β-unsaturated α-halo esters and α-choroamides through a Mn*-mediated sequential olefination protocol of aldehydes with dichloro esters or amides and trihalo esters or trichloroamides, respectively.

Key words

manganese - elimination reactions - stereoselectivity - α,β-unsaturated esters - α,β-unsaturated amides - metalation

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Aldrich catalogue (2009-2010): manganese powder (325 mesh): 250 g = 44 ı.

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When the minor diastereoisomer was not observed the E/Z ratio was assigned >98:2.