Table 1. Summary of System Ring Openings (ROs) and Modifications.

sys no.	name	RO	modifications
a	cellulose	no	none
b	23Ald	yes	aldehyde at C2 and C3
c	23DAC	yes	hydroxy group at C2 and C3
d	23Amin	yes	hydroxylamine on C2 and C3
e	23Carb	yes	carboxylic acid group on C2 and C3
f	6Carb	no	carboxylic acid group on C6
g	23Ald6Carb	yes	aldehyde at C2 and C3 and carboxylic acid group on C6
h	23DAC6Carb	yes	alcohol at C2 and C3 and carboxylic acid group on C6
i	236Carb	yes	carboxylic acid group at C2 and C3 and on C6