HMBC L HMBC F:l H-H COSY Spin System Located the Positions of Carbonyl Groups by HMBC CH CH H.C 1 400 H2C CH3 OH H O O H 4 H 3 H HO H 2 CH3 HMBC 401 2 O 3 1 4 5 8 O 7 6 1' 6' 2' 5' 3' 4' O O 7' O O H H HMBC 402 O O HO O OH OH HO H H H H HMBC 403 H-10 H-9 H-5 H-20a H-20b H-3' Ph-H H-2' H-13 H-3 H-14a O O H H O HO O 1 3 5 7 9 13 11 15 17 18 19 20 1' 2' 3' CH3 O H3C O 4' 5' 6' 7' O O H H O HO O 1 13 5 17 18 20 1' 3' CH3 O H3C O 4' 5' 6' 7' HMBC Mo 404 st Protons Were Omited for the Clearity 1H-1H COSY Spin System O O O O O H H 1 H- 1 H COSY Long-range 1 H- 1 H COSY CH3 O CH3 O H3C O The sign of coupling Geminal coupling (2J) Vicinal coupling (3J) Long range coupling (4J, 5J) Spin system 405 Located the Positions of Carbonyl Groups by HMBC O O O O O H H 1 H- 1 H COSY Long-range 1 H- 1 C COSY CH3 O CH3 O H3C O OH