"Tetrahydro" in this case does not necessarily mean that there are four additional hydrogen atoms attached. It's called like that because the core, without any substituents, is a tetrahydropyrimidine. Think of this compound as a pyrimidine, then you add four hydrogen atoms to get a tetrahydropyridine and *then* you add the ketone and thioketone. Two of the four originally added hydrogen atoms disappear, but the name stays. It's a bit confusing.
Seems wrong... I can only assume it's because they have the tautomer with both ring nitrogens having an N-H bond as the lactam/thiolactam form rather than cyclic imidate/thioimidate?
edit: the iupac name is correct. I’m not seeing why that choice was made, though.
I’m not following their reason.
This is a pyramidone, derived from a pyrimidine. Both are aromatics, both are fully unsaturated.
Both are correct. OP's name starts from a pyrimidine core, while ChemDraw's suggested name already starts from a pyrimidinone core, already featuring the ketone. So you only have to formally add two more hydrogen atoms to then replace one of them with a thioketone, hence only dihydro.
"Tetrahydro" in this case does not necessarily mean that there are four additional hydrogen atoms attached. It's called like that because the core, without any substituents, is a tetrahydropyrimidine. Think of this compound as a pyrimidine, then you add four hydrogen atoms to get a tetrahydropyridine and *then* you add the ketone and thioketone. Two of the four originally added hydrogen atoms disappear, but the name stays. It's a bit confusing.
This.
Eh even if this is correct logically and for proper naming and identification sakes you would not include the “tetrahydro” prefix I would think
Seems wrong... I can only assume it's because they have the tautomer with both ring nitrogens having an N-H bond as the lactam/thiolactam form rather than cyclic imidate/thioimidate?
You are wright. It looks like it´s an error to me too. That class of drugs are derivated from barbituric acid, btw.
The hydro's are silent in this case!
Naming is correct. Formally, you have to hydrogenate two C-N double bonds to be able to add the thio and oxo substituents.
So it's not called tetrahydro for having 4 hydrogens, but for being derived from a compound which has 4 hydrogens right?
edit: the iupac name is correct. I’m not seeing why that choice was made, though. I’m not following their reason. This is a pyramidone, derived from a pyrimidine. Both are aromatics, both are fully unsaturated.
Exactly. To make it more clear, try drawing the structure of the parent heterocycle without substituents.
Are you certain on the name? Chemdraw suggested name is "6-methyl-2-thioxo-2,3-dihydropyrimidine-4(1H)-one
Both are correct. OP's name starts from a pyrimidine core, while ChemDraw's suggested name already starts from a pyrimidinone core, already featuring the ketone. So you only have to formally add two more hydrogen atoms to then replace one of them with a thioketone, hence only dihydro.