88586-05-4Relevant academic research and scientific papers
Enzyme-catalysed Asymmetric Synthesis, IV. - Synthesis of Homochiral Building Blocks for the Enantioselective Total Synthesis of Cyclopentanoids with an Esterase-catalysed Asymmetric Reaction as Key Step
Gais, Hans-Joachim,Lukas, Karl L.,Ball, Walter A.,Braun, Siegmar,Lindner, Hans J.
, p. 687 - 716 (2007/10/02)
An efficient synthesis of the homochiral building blocks 2a and ent-2a based on the "enantiotopos-enzyme concept" for the total synthesis of cyclopentanoids is described.Key steps thereof are the almost quantitative PLE-catalysed asymmetric hydrolysis of the meso-diester 8 to the homochiral hemiester 9, whose absolute configuration was determined by crystal structure analysis of the (-)-ephedrine salt 12, the preparation of optically pure 9 and ent-9 by a racemate resolution of rac-9 using (+)- and (-)-ephedrine, the enantiodivergent synthesis of the lactones 18 and ent-18 from 9, as well as the enantioconvergent synthesis of 18 or ent-18 from 9 and ent-9 by optional chemoselective reduction of the ester and carboxy group, and finally the regioselective Dieckmann cyclisation of the isomeric diesters 23b/24b and ent-23b/ent-24b, respectively, to give the cyclopentanoid target compounds 2a and ent-2a.The structures of 23b, 24b, rac-2b, and rac-29 were determined by INADEQUATE-13C-NMR experiments.Dieckmann cyclisation of the trans-diester rac-31 also leads to rac-2a and rac-26a.
