Substrate Evaluation of<i>Rhodococcus erythropolis</i>SET1, a Nitrile Hydrolysing Bacterium, Demonstrating Dual Activity Strongly Dependent on Nitrile Sub-Structure
作者:Tracey M. Coady、Lee V. Coffey、Catherine O'Reilly、Claire M. Lennon
DOI:10.1002/ejoc.201403201
日期:2015.2
Rhodococcus erythropolis SET1, a novel nitrilehydrolysing bacterial isolate, has been undertaken with 34 nitriles, 33 chiral and 1 prochiral. These substrates consist primarily of β-hydroxy nitriles with varying alkyl and aryl groups at the β position and containing in several compounds different substituents α to the nitrile. In the case of β-hydroxy nitriles without substitution at the α position
Enantioselective Ring Opening of Epoxides with Cyanide Catalysed by Halohydrin Dehalogenases: A New Approach to Non-Racemic β-Hydroxy Nitriles
作者:Maja Majerić Elenkov、Bernhard Hauer、Dick B. Janssen
DOI:10.1002/adsc.200505333
日期:2006.3
Halohydrindehalogenases (HheA, HheB and HheC) were found to efficiently catalyse a carbon-carbon bond forming reaction between terminal aliphatic epoxides and cyanide, yielding β-hydroxynitriles. With all three enzymes nucleophilic ringopening of epoxides proceeds with high regioselectivity to the β-carbon atom. Activity, enantioselectivity and enantiopreference depend on the type of enzyme and
Thiacrown Ether Technology in Lipase-Catalyzed Reaction: Scope and Limitation for Preparing Optically Active 3-Hydroxyalkanenitriles and Application to Insect Pheromone Synthesis
Both reaction rate and enantioselectivity in Pseudomonas cepacia lipase (PCL)-catalyzed hydrolysis of 3-hydroxyalkanenitrile acetates were significantly changed by the addition of catalytic amounts of thiacrown ether (1,4,8,11-tetrathiacyclotetradecane). Although the-reaction rate of various nitriles was accelerated, the enantioselectivity greatly depended on the nature of the substrate. Among 10 substrates tested, thiacrown ether offered highest enantioselectivity in PCL-catalyzed hydrolysis of 1-(cyanomethyl)propyl acetate. Forty or more times this crown ether, molarity based on the enzyme, was required to attain an acceptably high reaction rate and enantioselectivity. Applying this technology, we succeeded in synthesizing the optically pure attractant pheromone of ant Myrmica scabrinodis (A), (R)-3-octanol and its antipode of (S)-isomer in good overall yields.
Rhodium-Catalyzed Enantioselective Intermolecular Hydroalkoxylation of Allenes and Alkynes with Alcohols: Synthesis of Branched Allylic Ethers
作者:Zi Liu、Bernhard Breit
DOI:10.1002/anie.201603538
日期:2016.7.11
Regio‐ and enantioselective additions of alcohols to either terminal allenes or internal alkynes provides access to allylic ethers by using a RhI/diphenyl phosphate catalytic system. This method provides an atom‐economic way to obtain chiral aliphatic and aryl allylic ethers in moderate to good yield with good to excellent enantioselectivities.
通过末端Rh I /二苯基磷酸酯催化系统,将醇的区域和对映体选择性加成到末端异戊烯或内部炔烃中,即可获得烯丙基醚。该方法提供了一种原子经济的方法,可以以中等至良好的收率以及良好至优异的对映选择性获得手性脂肪族和芳基烯丙基醚。