Synfacts 2006(10): 1019-1019  
DOI: 10.1055/s-2006-949276
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Stereoselective Homoallylation of Aldehydes and Ketones

Contributor(s): Mark Lautens, Andrew Martins
M. Kimura, A. Ezoe, M. Mori, K. Iwata, Y. Tamaru*
Nagasaki University, Japan
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Publikationsverlauf

Publikationsdatum:
21. September 2006 (online)

Significance

In the presence of catalytic Ni(acac)2 and stoichiometric Et3B or Et2Zn, 1,3-dienes are added to aldehydes and ketones to stereoselectively afford homoallylation products. Aromatic aldehydes react in the presence of Et3B with 1,3-anti selectivity whereas aliphatic aldehydes react in the presence of Et2Zn to give exclusively 1,3-anti products. Terminally substituted dienes generally afford 1,2-anti products, except hydroxyterminal dienes which afford 1,2-syn products. Less reactive moieties such as ketones and cyclohexadiene required Et2Zn, and afforded the product in moderate yields, with cyclohexadiene affording allylation, not homallylation products. Catalyst loadings as low as 1 mol% were used on a 50-mmol scale and the diene loading was decreased to 1.1 equivalents. The method was applied to a 10-g scale reaction of isoprene and dehydrocinnamaldehyde, affording product in 80% yield.