Kinetic resolution displaying zeroth order dependence on substrate consumption: copper-catalyzed asymmetric alcoholysis of azlactones.
Kinetic resolution of 4-alkyl-2-aryl-5-oxo-4,5-dihydrooxazole-4-carboxylic acid esters (azlactones 1) were achieved by copper-DTBM-SEGPHOS catalyzed alcoholysis reaction with good selectivity (12 examples). Variation of ee of unreacted substrates 1 and products 2 with conversion was found to follow the theoretical line of zeroth-order kinetic resolution, for which the selectivity profiles and graphical analysis were presented for the first time. The efficiency of resolution in zeroth-order reaction is higher than first-order reaction. For example, the reaction with 1a afforded (S)-1a (99% ee) and (R)-2a (74% ee) at 57% conversion, where the k(rel) values were calculated to be 6.7 as zeroth-order kinetic resolution and 37 as first-order kinetic resolution.
Catalysis Research Center and Division of Chemistry, Graduate School of Science, Hokkaido University, SORST and CREST, Japan Science and Technology Agency (JST), Sapporo. tokunaga@cat.hokudai.ac.jp
Makoto
M
Tokunaga
Junya
J
Kiyosu
Yasushi
Y
Obora
Yasushi
Y
Tsuji
D002384:Catalysis; D003300:Copper / Q000737:chemistry; D007700:Kinetics; D007783:Lactones / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry*; D013237:Stereoisomerism
D007783:Lactones; D010080:Oxazoles; D003300:Copper