903529-16-8Relevant articles and documents
Asymmetric reductions of ethyl 2-(benzamidomethyl)-3-oxobutanoate by yeasts
Gandolfi, Raffaella,Cesarotti, Edoardo,Molinari, Francesco,Romano, Diego,Rimoldi, Isabella
scheme or table, p. 411 - 414 (2009/09/08)
The stereoselective reduction of ethyl 2-(benzamidomethyl)-3-oxobutanoate 1 using yeasts was investigated among a restricted number (12) of yeasts. Kluyveromyces marxianus var. lactis CL69 diastereoselectively produced (2R,3S)-ethyl 2-(benzamidomethyl)-3-hydroxybutanoate 2, whereas Pichia glucozyma CBS 5766 gave (2S,3S)-2 as the major stereoisomer. The biotransformations were independently optimized for minimizing by-product formation and maximizing the diastereoselectivity. Under optimized conditions, K. marxianus var. lactis CL 69 gave the (2R,3S)-ethyl 2-(benzamidomethyl)-3-hydroxybutanoate 2 with ee > 99% and de = 98%, while P. glucozyma CBS 5766 allowed for the production of (2S,3S)-2 with ee > 99% and de = 86%.
Process for the manufacture of 4-acyloxy-3-hydroxyethyl-azetidinones
-
, (2008/06/13)
The invention relates to a novel process for the manufacture of (3R,1'R)-4-acyloxy-3-(1'-hydroxyethyl)-2-azetidinones of formula STR1 in which R1 represents lower alkyl or aryl, by enantioselective reduction of the carbonyl group in a suitable α-acylaminomethyl-acetoacetic acid ester, cyclisation of the resulting α-acylaminomethyl-β-hydroxybutyric acid ester to a 5,6-dihydro-1,3,4H-oxazine with inversion of the carbon atom carrying the hydroxy group, equilibration to form the preferred trans-substituted dihydrooxazine, recleaving to form the configuratively uniform α-aminomethyl-β-hydroxybutyric acid, ring-closure to form the β-lactam and oxidative acylation at C(4) of the β-lactam. Compounds of formula I can be used as starting materials for the manufacture of β-lactam antibiotics. The invention relates also to novel intermediates.
