17299-07-9Relevant articles and documents
New continuous production process for enantiopure (2R,5R)-hexanediol
Haberland, Juergen,Hummel, Werner,Daussmann, Thomas,Liese, Andreas
, p. 458 - 462 (2002)
A new continuous production process has been developed for optically active pure (2R,5R)-hexanediol. The process uses resting whole cells of Lactobacillus kefir DSM 20587 as a biocatalyst. The reduction of (2,5)-hexanedione to (2R,5R)-hexanediol was carried out in a 2-L continuously operated membrane reactor. Conversion of (2,5)-hexanedione was nearly quantitative and the selectivity between product and intermediate was 78% for the product. Enantioselectivity and diastereoselectivity were >99% for the whole period. The productivity of L. kefir could be increased by factor 30. (2R,5R)-Hexanediol was continuously produced over 5 days with a space-time yield of 64 g·L-1·d-1.
On the mechanism of the unexpected facile formation of meso-diacetate products in enzymatic acetylation of alkanediols
Edin, Michaela,Baeckvall, Jan-E.
, p. 2216 - 2222 (2003)
The mechanism of the unexpected facile formation of meso-diacetate previously observed in the enzymatic resolution of dl/meso mixtures of 2,4-pentanediol and 2,5-hexanediol with Candida antarctica lipase B has been elucidated. It was found that the formation of meso-diacetate proceeds via different mechanisms for the two diols. Enzyme-catalyzed acylation of AcO-d3 labeled (R)-monoacetates of meso-2,4-pentanediol and meso-2,5-hexanediol and analysis of the mesodiacetates obtained show that the former reaction proceeds via intramolecular acyl migration while the latter occurs via direct S-acylation of the alcohol. For the (R)-monoacetate of (R,S)-2,4-pentanediol the intramolecular acyl migration was fast and therefore direct S-acylation by the external acyl donor is suppressed. For the hexanediol monoacetate the rate ratio (pseudo E value) between (5R,2R)- and (5R,2S)-5-acetoxy-2-hexanol was experimentally determined to be kR,R/kR,S = 25, which is about 10-20 times lower than the E value for 2-pentanol and 2-octanol. In a preliminary experiment it was demonstrated that facile acyl migration in the 1,3-diol derivative can be utilized to prepare syn-1,3-diacetoxynonane (β90% syn) in high enantioselectivity (β99% ee) via a chemoenzymatic dynamic kinetic asymmetric tyransformation of a meso/dl mixture of 1,3-nonanediol.
Absolute configuration for 1, n-glycols: A nonempirical approach to long-range stereochemical determination
Li, Xiaoyong,Burrell, Carmin E.,Staples, Richard J.,Borhan, Babak
, p. 9026 - 9029 (2012/07/13)
The absolute configurations of 1,n-glycols (n = 2-12, 16) bearing two chiral centers were rapidly determined via exciton-coupled circular dichroism (ECCD) using a tris(pentafluorophenyl)porphyrin (TPFP porphyrin) tweezer system in a nonempirical fashion devoid of chemical derivatization. A unique "side-on" approach of the porphyrin tweezer relative to the diol guest molecule is suggested as the mode of complexation.
Dynamic kinetic asymmetric transformation of 1,4-diols and the preparation of trans-2,5-disubstituted pyrrolidines
Borén, Linnéa,Leijondahl, Karin,B?ckvall, Jan-E.
experimental part, p. 3237 - 3240 (2009/08/17)
Dynamic kinetic asymmetric transformation (DYKAT) of a series of 1,4-diols is carried out with Candida antarctica lipase B (CALB), Pseudomonas cepacia lipase II (PS-C II), and a ruthenium catalyst. A β-chloro-substituted 1,4-diol is successfully transformed into an optically pure 1,4-diacetate, which is a highly useful synthetic intermediate. The usefulness of the optically pure 1,4-diacetates is demonstrated by the synthesis of enantiopure 2,5-disubstituted pyrrolidines.
