反应详情

0.45 g of rhodium/Al2O3 catalyst is added to 15 g of (S)-2-acetamido-3-ethoxycarbonyl-2-penten-4-olide dissolved in 100 ml of ethyl acetate and the whole is hydrogenated at 50° C. and 50 bars for 21 hours and worked up as in Example 14. The ratio of the diastereoisomers of the crude product exhibited by HPLC analysis is (2R,3S,4S):(2S,3R,4S):(2R,3R,4S)=approximately 85:13:2. Diastereoisomerically pure title compound is obtained by crystallisation from ethyl acetate, [α]D20 =-183.2° (3% in CHCl3), m.p. 165°-167° C.

1. customis hydrogenated at 50° C.