Kawa Constituents — Hansel 
299 
/ C x 
ch 2 ch 2 
CH=CH~C C=0 
II I 
0 OH 
+ H 2 
0 
I! 
\ 
CHo CH 2 
1 l 
CH = CH-CH C = 0 
n ohho / 
0 
II 
/" C '\ 
CH CH 2 
CH=CH — C 
c=o 
OH HO 
cyclyzat ion 
OH 
CH = CH-^^X 
0^0 
yangonin type 
+ H 2 
(interruption of the =t conjugation) 
CH 2 -CH 2 -^ 0 A 5 . 0 
7.8 - dihydroyangonin type 
(not found in the plant) 
Fig. 6. Biosynthetic scheme showing various stages of hydrogenation. 
