The β-amino alcohol 1b−Ti(Oi-Pr)4 complex has been shown to catalyze the enantioselective cyanosilylation of aldehydes efficiently. In the presence of 5 mol % of 1b−Ti(Oi-Pr)4 complex catalyst, the aromatic, conjugated, heteroaromatic, and aliphatic aldehydes were converted to their corresponding trimethylsilyl ethers of cyanohydrins in 90−99% yields with up to 94% ee under mild conditions.
β-氨基醇1b -Ti(O i -Pr)4配合物已显示出可有效催化醛的对映选择性氰基硅烷化反应。在5摩尔%的1b -Ti(O i -Pr)4络合催化剂存在下,芳族,共轭,杂芳族和脂族醛以90-99%的产率转化为相应的氰醇三甲基甲硅烷基醚,产率最高为94 %ee在温和条件下。
Highly enantioselective cyanosilylation of aldehydes catalyzed by a Lewis acid–Lewis base bifunctional catalyst
A new bifunctional asymmetric catalyst containing a Lewis acid and a Lewis base (1) was developed and applied to the catalytic asymmetric cyanosilylation of aldehydes. The products were obtained generally with excellent enantiomeric excess. The experiments using the control catalyst (5) and the catalyst containing more electron-rich phosphine oxide (6) suggest that the catalyst 1 should promote the
Development of a family of β-amino alcohol ligands with two stereocenters for highly efficient enantioselective trimethylsilylcyanation of aldehydes
作者:Jing-Song You、Han-Mou Gau、Michael C. K. Choi
DOI:10.1039/b006128j
日期:——
The asymmetric addition of Me3SiCN to aldehydes catalyzed by titanium(IV) complexes of N-sulfonylated derivatives of β-amino alcohols gave excellent ee’s up to 96% ee.
A new (R)-hydroxynitrile lyase from Prunus mume: asymmetric synthesis of cyanohydrins
作者:Samik Nanda、Yasuo Kato、Yasuhisa Asano
DOI:10.1016/j.tet.2005.08.105
日期:2005.11
A new hydroxynitrile lyase (HNL) was isolated from the seed of Japanese apricot (Prunus mume). The enzyme has similar properties with HNL isolated from other Prunus species and is FAD containing enzyme. It accepts a large number of unnatural substrates (benzaldehyde and its variant) for the addition of HCN to produce the corresponding cyanohydrins in excellent optical and chemical yields. A new HPLC
Chiral linear polymers bonded alternatively with salen and 1,4-dialkoxybenzene: synthesis and application for Ti-catalyzed asymmetric TMSCN addition to aldehydes
the asymmetricaddition of TMSCN to aldehydes while the selectivity of the polymer catalyst is identical to that of the monomer. The reactions are efficient affording the cyanohydrins with up to 88% ee. The selectivity of the polymer based catalyst 9a is found to be the same to that of the monomer 10a. The reaction provides the advantages of simplified product isolation and easy recovery and recyclability
已经完成了以salen和1,4-二辛氧基苯为交替链段的手性线性聚合物1a – b的合成。GPC分析显示出对应于约3的分子量。15个(M w = 10,999,M n = 9165和PDI = 1.20)1a和ca的重复单元。 对于1b重复8(M w = 8547,M n = 7883和PDI = 1.08)重复单元。用Ti(O i Pr)4研究了聚合物1a – b作为可再循环的催化剂,用于将TMSCN不对称加成到醛中,而聚合物催化剂的选择性与单体的选择性相同。该反应有效地提供了高达88%ee的氰醇。发现基于聚合物的催化剂9a的选择性与单体10a的选择性相同。该反应的优点是简化了产物分离,并且聚合物催化剂9a易于回收和再循环,而没有任何活性或选择性的损失。