limit a rule only to the end group

We prefer to R-SO-OH and R-O-SO-OH if SO2 is the end group;


R1-S(=O)(=O)-R2 if SO2 is NOT the end group.


The following rule not work for above purpose,


"[O:3]=([C,N,O,F,Cl,Br,I:4])=[O:2]>>[O:3]=([C,N,O,F,Cl,Br,I:4])[O-:2]"


How to limit the rule to end groups only or Would you suggest other tranformation rules? Thank you

Please upload two examples as images. One with the current transformation that is wrong, and one with the desired one.

image attached.


Two cases (up and down).


Structure on the right is with expected form (red box)


to its case. Thank you

Try this:


[C,N,O,F,Cl,Br,I:4][S;!$(S[OH]),!$(S[O-]):1](=[O:3])=[O:2]>>[O-:2]([C,N,O,F,Cl,Br,I:4])=[O:3]





It contains an additional recursive SMARTS part specifying, that the sulfur atom is not connected to OH or O-.