反应详情

The only publication describing the preparation procedure of (2-hydroxy-3-oxo-cyclopent-1-enyl)-acetic acid esters, particularly the corresponding tAm ester is described by Reile et al. (Reile I., Paju, A.; Eek, M.; Pehk, T.; Lopp, M. Aerobic Oxidation of Cyclopentane-1,2-diols to Cyclopentane-1,2-diones on Pt/C Catalyst. Synlett, 2008 (3), 347-350). According to that procedure 2-cyclopentene-1-acetic acid is transformed to 2-cyclopentene-1-acetic acid tAm ester by transesterification according to a known procedure (Frei, U., Kirchmayr, R. EP 0278914). The resulted 2-cyclopentene-1-acetic acid tAm ester is dihydroxylated by using fiber bound OsO4 (0.1 mol %) and NMO (1.3 equiv) in H2O-tBuOH 1:3 mixture at 60° C., resulting in (2,3-dihydroxycyclopentenyl)-acetic acid tAm ester. This compound is oxidized with air oxygen in the presence of 5 mol % Pt/C catalyst in MeCN—H2O 1:1 mixture, in the presence of 1 equivalent of LiOH. The target compound (2-hydroxy-3-oxo-cyclopent-1-enyl)-acetic acid tAm ester was obtained in 28% yield after separation and purification.

1. customat 60° C.