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。
Immobilized Baliospermum montanum hydroxynitrile lyase catalyzed synthesis of chiral cyanohydrins
作者:Nisha Jangir、Santosh Kumar Padhi
DOI:10.1016/j.bioorg.2018.11.017
日期:2019.3
Hydroxynitrilelyase (HNL) catalyzed enantioselective CC bond formation is an efficient approach to synthesize chiral cyanohydrins which are important building blocks in the synthesis of a number of fine chemicals, agrochemicals and pharmaceuticals. Immobilization of HNL is known to provide robustness, reusability and in some cases also enhances activity and selectivity. We optimized the preparation
羟基腈裂解酶(HNL)催化的对映选择性CC键形成是合成手性氰醇的有效方法,手性氰醇是许多精细化学品,农用化学品和药物合成中的重要组成部分。已知HNL的固定可提供鲁棒性,可重复使用性,并且在某些情况下还可以增强活性和选择性。我们通过交联酶聚集体(CLEA)法优化了褐藻(Balospermium montanum HNL)固定化的制备(BmHNL),并通过SEM对其进行了表征。使用CLEA-BmHNL进行了生物催化参数的优化,以从苯甲醛获得最高的%转化率和ee(S)-扁桃腈的ee。优化的反应参数为:反应时间20分钟,7 U CLEA-BmHNL,1.2 mM底物和300 mM柠檬酸盐缓冲液pH 4.2,合成了约99%ee和约60%转化率的(S)-扁桃腈。与其他CLEA-HNL不同,在CLEA-BmHNL生物催化中添加有机溶剂的ee%或产物转化率没有提高。CLEA-BmHNL可以成功地连续使用八
Asymmetric Hydrocyanation of Aldehydes Using Chiral Titanium Reagents
Two highly enantioselective methods for hydrocyanation of aldehydes were developed by using chiral alkoxytitanium reagents. Treatment of benzaldehyde with cyanotrimethylsilane in the presence of a chiral alkoxytitanium affords mandelonitrile in good chemical and optical yields. By the use of the chiral cyanotitanium reagent generated in situ from the chiral alkoxytitanium and cyanotrimethylsilane, aliphatic aldehydes are converted into the corresponding cyanohydrins in a highly enantioselective manner.
communis) have been applied to catalyze the asymmetricsynthesis of (R)‐4‐methylsulfanylmandelonitrile, a key building block of thiamphenicol and florfenicol. Here, four hydroxynitrile lyase (HNL) isozymes from Badamu were cloned and heterologously expressed in Pichia pastoris. The biochemical properties and catalytic performances of these isozymes were comprehensively explored to evaluate their efficiency
benzo-ketal aldehyde which was proved to be resistant against racemization during the deprotection step, with dramatically improved productivity (>95% conversion vs <1%). X-ray structure analysis and kinetic study revealed the side chain of L331 tunes the substrate adaptability of bulky and rigid benzo-ketal aldehyde, thereby facilitating the formation of a series of valuable unnatural cyanohydrins in high