1 BKN Ethyl 5-oxohexanoate 1.000 2 9J6 6-ethoxy-6-oxohexanoic acid 0.769 3 BKQ Ethyl levulinate 0.750 4 NLO O-methyl-L-norleucine 0.750 5 2JG (2s)-2-amino-3-oxopropyl hexanoate 0.714 6 OBK 7-ethoxy-7-oxidanylidene-heptanoic acid 0.714