Default heteroatom placement for oxazine

Issue #9 resolved
Steve Chapman
created an issue

4-propyl-9-hydroxynaphthoxazine fails parse with "Atom is in unphysical valency state! Element: O valency: 3"

IUPAC's default heteroatom placement for "oxazine" seems to be 1,4, but the parser seems to be defaulting to 1,2.

http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=57533&loc=ec_rcs

Comments (3)

  1. Daniel Lowe repo owner

    I don't believe the IUPAC has codified what the default locants are on oxazine i.e. oxazine is ambiguous. Unfortunately some structure to name tools assume oxazine to be equal to 1,2-oxazine (cf. http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=12313776) so going with the structurally more common 1,4- motif would also introduce errors. I could in principle add naphthoxazine but even the definition of this isn't entirely clear. I could only find one other hit for it on PubChem and it used the 1,2-positions (http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=66604612) As this record comes from Surechem it wouldn't be surprising if the structure came from name to structure so using it as a strong counterargument would be rather circular reasoning!

  2. Daniel Lowe repo owner

    ...Good spot. I think it is an oversight though. I've aquired a 2012 draft of this document which no longer contains the table with 4H-oxazine and the like. (All mentions of oxazine are preceded by locants)

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