Stereoselective nucleophilic formylation and cyanation of alpha-alkoxy- and alpha-aminoaldehydes.
The spontaneous 1,2-addition of formaldehyde N,N-dialkylhydrazones to carbohydrate-derived alpha-alkoxyaldehydes takes place under neutral conditions and in the absence of catalysts or promoters to afford the corresponding alpha-hydroxyhydrazones in good to excellent yields and with highly anti diastereoselectivities. Subsequent transformations of the hydrazono group into aldehydes and nitriles following known procedures provide a new entry into the homologation of carbohydrates and the synthesis of cyanohydrins, respectively. Additionally, reaction of methyleneaminopyrrolidine with N-Boc-protected alpha-aminoaldehydes from natural amino acids efficiently affords the corresponding adducts under the same conditions. From these adducts, a variety of biologically interesting alpha-hydroxy-beta-aminocarbonyl compounds can be accessed upon manipulation of the hydrazone moiety.
Fernández
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Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Apartado de Correos 553, E-41071 Seville, Spain.
Martín-Zamora
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E
Pareja
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C
Lassaletta
J M
JM