Baeza A, Nájera C, Sansano JM, Saá JM. Binolam-AlCl: A Two-Centre Catalyst for the Synthesis of Enantioenriched CyanohydrinO-Phosphates.
Chemistry 2005;
11:3849-62. [PMID:
15776489 DOI:
10.1002/chem.200401290]
[Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The enantioselective synthesis of cyanohydrin O-phosphates by using in situ generated bifunctional catalysts (R)- or (S)-3,3'-bis(diethylaminomethyl)-1,1'-binaphthol-aluminium chloride (binolam-AlCl) is reported. The reaction, which can be described as an overall cyano-O-phosphorylation of aldehydes, has a wide scope and applicability. Evidence is also provided, including ab initio and DFT calculations, in support of supported by the Lewis acid/Brønsted base (LABB) dual role of the catalyst in inducing first the key enantioselective hydrocyanation, which is then followed by O-phosphorylation. A brief screening of the synthetic usefulness of the resulting cyanohydrin O-phosphates unveiles some interesting applications. Among them, chemoselective hydrolysis, reduction and palladium-catalysed nucleophilic allyl substitution, thereby leading to enantiomerically enriched alpha-O-phosphorylated alpha-hydroxy esters, beta-amino alcohols and gamma-cyanoallyl alcohols, respectively. Naturally occurring (-)-tembamide and (-)-aegeline are synthesised accordingly.
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