Synthesis of Chiral 1-Arylalkan-1-ols Using Crude Enzymes
摘要:
Enantioselective hydrolysis of racemic l-acetoxy-l-arylalkanes has been examined by two selected enzymes, crude pig liver acetone powder and crude goat liver acetone powder, providing l-arylalkan-l-ols in high optical purities.
Expanding substrate scope of lipase-catalyzed transesterification by the utilization of liquid carbon dioxide
摘要:
Secondary alcohols having bulky substituents on both sides of the chiral center are often poor substrates for most lipases. Here we reported that substrate scopes of two of the most used lipases, Candida antarctica lipase B and Burkholderia cepacia lipase, were found to be expanded toward more bulky secondary alcohols such as 1-phenyl-1-dodecanol and 2-methyl-1-phenyl-1-propanol by simply using them in liquid carbon dioxide as a solvent. The effects of solvents, reaction pressure, and pre-treatment of the enzyme with liquid CO2 on this acceleration phenomenon were also studied. (C) 2015 Elsevier Ltd. All rights reserved.
Nucleophilic Substitutions of Alcohols in High Levels of Catalytic Efficiency
作者:Tanja Stach、Julia Dräger、Peter H. Huy
DOI:10.1021/acs.orglett.8b01023
日期:2018.5.18
A practical method for the nucleophilicsubstitution (SN) of alcohols furnishing alkyl chlorides, bromides, and iodides under stereochemical inversion in high catalytic efficacy is introduced. The fusion of diethylcyclopropenone as a simple Lewis base organocatalyst and benzoyl chloride as a reagent allows notable turnover numbers up to 100. Moreover, the use of plain acetyl chloride as a stoichiometric
Alkylbenzenes are selectively functionalised to the corresponding acetates by nitric aerobic oxidation catalysed by N-hydroxyphthalimide and iodine. With cyclohexane the oxidation leads to a mixture of cyclohexyl acetate and trans-2-iodocyclohexyl acetate. The mechanism is discussed.
The reactions of styrene and trans-β-methylstyrene with lead tetraacetate in acetic acid are greatly influenced by ultrasonic irradiation to give products resulting mostly from radical chain pathways, whereas mechanical agitation gives products only from ionic processes.
The first Ritter-type reaction of alkylbenzenes with nitriles has been successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a key catalyst. Thus, treatment of ethylbenzene with ammonium hexanitratocerate(IV) (CAN) in the presence of a catalytic amount of NHPI in EtCN under argon produced the corresponding amide in good selectivity.