sulfonamide chemical term cannot be used to match nitrogen?

Hi, I was trying to exclude sulfonamides from being reactants in a reaction using an amine.  However, specifying not a sulfonamide in the reactivity did not appear to exclude a sulfonamide from reacting.

not match(ratom(1), sulfonamide, 3)

Inspection of the SMARTS for sulfonamide (from https://docs.chemaxon.com/display/chemicalterms/Predefined+Functional+Groups+and+Named+Molecule+Groups) indicates that the nitrogen is specified not as an atom, but as a context for the sulfur atom:

[#6:1][$([SX4:2]([NX3:3])(=[OX1:4])(=[OX1:4])),$([SX4+2:2]([NX3:3])([OX1-:4])([OX1-:4]))]

modifying the SMARTS to make the nitrogen an explicit atom made the exclusion behave as expected:

[#6:1][$([SX4:2](=[OX1:4])(=[OX1:4])),$([SX4+2:2]([OX1-:4])([OX1-:4]))][NX3:3]

not match(ratom(1), "[#6:1][$([SX4:2](=[OX1:4])(=[OX1:4])),$([SX4+2:2]([OX1-:4])([OX1-:4]))][NX3:3]", 3)

Is it expected that context-only atoms are not matched as part of SMARTS?  Is there some reason the sulfonamide definition was set up not to match nitrogen?

Thanks!

You are right, the sulfonamide definition does not allow to match the nitrogen atom (context only atoms are not matched). We will update the definition of sulfonamide.

Great, thank you!