Enantioenriched cyanohydrin O-phosphates: Synthesis and applications as chiral building blocks*
Alejandro Baeza1, José M. Sansano1, José M. Saá2, and Carmen Nájera1
1Departamento de Química Orgánica e Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, E-03080 Alicante, Spain; 2Departamento de Química, Universitat de les Illes Balears, 07122 Palma de Mallorca, Spain
Abstract: Aluminum complexes of the chiral (R)- or (S)-3,3'-bis(diethylaminomethyl)-1,1'-bi-2,2'-naphthol (BINOLAM) ligand behave as efficient catalysts for the enantioselective cyanation-O-functionalization of aldehydes, thereby leading to enantiomerically enriched O-silyl, O-methoxycarbonyl, or O-phosphate derivatives of cyanohydrins. The enantioenriched cyanohydrin-O-phosphates are useful for the synthesis of several enantioenriched compounds such as α-hydroxy esters, β-amino alcohols, and γ-substituted α,β-unsaturated nitriles. Natural products such as (-)-aegeline and (-)-tembamide have been prepared in this manner.
Keywords: asymmetric catalysis; cyanohydrins; binolam; aluminum; palladium; copper.
*Paper based on a presentation at the 16th International Conference on Organic Synthesis (ICOS-16), 11-15 June 2006, Mérida, Yucatán, México. Other presentations are published in this issue, pp. 153-291.