Organic Letters 2012-06-01

The vinylogous aldol reaction of unsaturated esters and enolizable aldehydes using the novel Lewis acid aluminum tris(2,6-di-2-naphthylphenoxide).

Jeffrey A Gazaille, Tarek Sammakia

Index: Org. Lett. 14(11) , 2678-81, (2012)

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Abstract

The synthesis of the novel Lewis acid, aluminum tris(2,6-di-2-naphthylphenoxide) (ATNP), and its use in the vinylogous aldol reaction between methyl crotonate and enolizable aldehydes are described. ATNP is related to Yamamoto's Lewis acid, aluminum tris(2,6-diphenylphenoxide) (ATPH), but the 2-naphthyl groups more effectively block the α-position of aldehydes, enabling the selective enolization of crotonate esters in the presence of enolizable aldehydes. Vinylogous aldol reactions then proceed smoothly and in high yields with a variety of substrates.