20918-92-7Relevant academic research and scientific papers
Highly enantioselective acylation of rac-alkyl lactates using Candida antarctica lipase B
Lee, Yeon Soo,Hong, Joo Hee,Jeon, Nan Young,Won, Keehoon,Kim, Bum Tae
, p. 948 - 951 (2013/09/03)
By using Candida antarctica lipase B under mild conditions, the highly enantioselective acylation of alkyl (R)-lactate from racemic mixture with vinyl alkanoate has been accomplished. In this research effects of the organic solvent, the alkyl chain length of the alkyl lactates and of the vinyl alkanoates, and the reaction temperature on the enantiomeric excess as well as the reaction rate, were investigated. In all cases, only alkyl (R)-lactate was stereoselectively acylated at >99.5% ee. The lipase-catalyzed acylation rate of the alkyl lactates was affected by the nature of the organic solvents, but showed no correlation to log P of the solvent. The lipase-catalyzed acylation rate of the alkyl lactates was enhanced by increasing the chain length of the vinyl alkanoate from acetyl to butanoyl and by raising the reaction temperature to 65°C. Finally, the lipase-catalyzed acylation and subsequent vacuum distillation successfully provided both butyl (R)-O-butanoyllactate and butyl (S)-lactate in excellent yields (48%) and enantioselectivities (>99.5% ee) on a large scale. It is expected that the present method will prove to be more efficient in achieving the chiral resolution of racemic alkyl lactate than other conventional methods in terms of environmental friendliness and simplicity.
The Synthesis of Chiral Dimethyl Substituted Macrocyclic Polyether-Diester Ligands (1)
Jones, Brian A.,Bradshaw, Jerald S.,Izatt, Reed M.
, p. 551 - 556 (2007/10/02)
A new series of chiral macrocyclic polyether-diester ligands has been prepared from four chiral dimethyl substituted tetraethylene glycols (15a,b,16,17) and 2,6-pyridinecarbonyl chloride (products 5a-7), diglycolyl chloride (products (8-10), thiadiglycolyl chloride (product 11), 2,5-furandicarbonyl chloride (product 12), 4-chloro-2,6-pyridinedicarbonyl chloride (product 13), and 4-methoxy-2,6-pyridinedicarbonyl chloride (product 14).The chiral dimethyl substituted tetraethylene glycols (15a-17) were prepared from ethyl(S)-lactate.
