Asymmetric cyanohydrin synthesis from aldehydes and ketones using chiral metal (salen) complex as catalyst

Title
Asymmetric cyanohydrin synthesis from aldehydes and ketones using chiral metal (salen) complex as catalyst
Authors
Kim, S.S.
Keywords
salen, aldehydes, ketones, asymmetric synthesis
Issue Date
2006-05
Publisher
INT UNION PURE APPLIED CHEMISTRY
Abstract
Asymmetric addition of (CH3)(3)SiCN to carbonyl compounds and subsequent hydrolysis produces chiral cyanohydrins [1-3]. Such chiral compounds are useful intermediates for synthesis of pharmaceutics. The two functional groups (-OH and -CN) can be easily transformed into various homochiral ones including alpha-hydroxy acids [4,5], alpha-hydroxy aldehydes [6], alpha-hydroxy ketones [6], beta-hydroxy amines [5,6] and alpha-amino acid derivatives [7]. N-Methylmorphorin-N-oxide, cesium fluoride, potassium fluoride, and zirconium complex were, respectively, used as a catalyst for achiral silylcyanation [8-12] of aldehydes and ketones. Shibasaki has reported enantioselective catalytic additions of trimethylsilyl cyanide (TMSCN) to various ketones utilizing bifunctional ligand and Ti(OiPr)(4) or the lanthanide complexes [13]. The concept of dual activation was pioneered by Shibasaki's group. Deng first described the method of cyanosilylation of ketones employing chiral Lewis bases which are free of metal ions [14]. Snapper and Hoveyda described the addition of TMSCN to ketones catalyzed by peptidic chiral ligand and Al(OiPr)(3) [15]. Feng and Jiang employed chiral N-oxide/titanium(IV) complex for the cyanosilylation of ketones [16]. Feng utilized a catalytic double-activation method using chiral salen-Ti(IV) complex and various achiral N-oxides for the cyanosilylation of ketones [17]. Recently, Corey has shown that chiral oxazaborolidium salt is an excellent catalyst for the cyanosilylation of methyl ketones[18]. This method used TMSCN and diphenylmethyl phosphine oxide as co-reactants to generate Ph2MePOTMS(N=C:) as a reactive intermediate.
URI
http://dspace.inha.ac.kr/handle/10505/1809
ISSN
0033-4545
Appears in Collections:
College of Natural Science(자연과학대학) > Chemistry (화학) > Journal Papers, Reports(화학 논문, 보고서)
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