Naming bug in pyrimidotriazines

Hi,


I have the following smiles


O=c1nnc2[nH]c(=O)[nH]c(=O)c2[nH]1





Beilstein: 4,8-Dihydro-pyrimido[5,4-e][1,2,4]triazine-3,5,7-trione,


CAS: 4,8-Dihydro-pyrimido[5,4-e]-1,2,4-triazine-3,5,7-trione


ACDLabs 4,8-dihydropyrimido[5,4-e][1,2,4]triazine-3,5,7(6H)-trione





MARVIN


Preferred IUPAC Name = 3H,4H,5H,6H,7H,8H-pyrimido[5,4-e][1,2,4]triazine-3,5,7-trione


Traditional Name = 4H,6H,8H-pyrimido[5,4-e][1,2,4]triazine-3,5,7-trione





I remember that only those get a 1H,2H,3H which have a hydrogen attached.


Which is problematic with C5H3N5O3.





MarvinView 4.1.13, WINXP,


java version "1.5.0_06"


Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)


Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode)





I could reproduce the error with MSKETCH, but not with MVIEW.


To prevent this bug in the current version, switch to both (IUPAC and


traditional) this will show the correct name Also turn on/off fragment


style.





In principle such an error could be avoided by running the whole


PubChem against the Naming function or use the Name2Structure


and comparing the results to each other, or by checking the name


afterwards again with a independent parser (which could reveal such problems).





Tobias

Hi Tobias,





There are several options about displaying indicated hydrogens. Take this example, which I believe illustrates the same situation, from IUPAC's Prefered IUPAC Names (PIN) document: O=C1OC=CC=C1





The PIN for this structure is, according to the standard: 2H-pyran-2-one





The idea behind this convention is that the structure is a 2H-pyran, C1OC=CC=C1, on which an oxo group is attached at locant 2. Another way to look at it is that Hs indicate the removal of aromatic bonds (as if by hydrogenation).





We follow the standard and therefore generate 2H-pyran-2-one. This is correct even though there is no hydrogen at location 2H.





We understand that this is not the traditional way to represent hydrogenation and substitution. That is why you also have the option in marvin to generate Traditional names, which do not have the additional Hs. As you saw, in that mode we agree with ACDLabs' tool to indicate hydrogens in positions 4, 6 and 8 (with a different syntax). That the others are missing 6H seems wrong to me since position 6 has an hydrogen, unless there is another traditional rule I am unaware of.





Daniel