orthonym.rules.linear_phane_screen#

Note

Internal API. Names and behaviour may change between releases.

Can a linear phane name be the PIN of this molecule? (2); fail closed).

### **** Preferred IUPAC names in phane nomenclature (the Blue Book),

  1. (:23829): “linear phanes consist of four or more rings or ring systems, two of

which must be terminal, and together with acyclic atoms or chains must consist of at least seven nodes (components)”; (:23901): “Phane nomenclature is used to generate preferred IUPAC names for ring assemblies and linear acyclic/cyclic compounds that include a minimum of seven nodes including at least four rings or ring systems, two of which must be terminal, even though the compounds could also be named by substitutive or multiplicative nomenclature.”

The phane parent still has to win first: “These criteria must always be applied before those applicable to rings and ring systems (see and to chains (see “, :18873), and a linear phane is one of the ring-system types (“(f) linear phane system”, :19541). A principal characteristic group whose carbonyl carbon and heteroatom are both skeletal nodes (an acyclic -CO-NH-, -CO-O-) or whose nitrogen is a node (an -NH- between two rings) is cited by a phane name as ‘oxo’ + ‘aza’/’oxa’ or as ‘aza’, never as the suffix: the phane parent cites fewer suffixes than the substitutive parent and is not the PIN,:18875). Nilotinib, whose every qualifying path runs through its amide carbon and nitrogen, keeps the benzamide PIN. A ketone or pseudoketone carbon on the skeleton is different: the phane name cites it as ‘-one’ (“an acyclic compound having a carbonyl group linked to a heteroatom belonging to a ring or ring system”,:1878;,:33127 “An N-acyl group attached to a nitrogen atom of a heterocyclic system is now preferably named as a pseudoketone”), so such a group never takes the phane out of the running (venadaparib, olaparib).

This screen answers True (a phane name may be the PIN: a substitutive name is then a general name, never a certified PIN) unless it can show that no qualifying path exists, or that every qualifying path takes in a non-ring atom of every principal-group instance and cites none of them as ‘-one’. Simplified skeleton,:14857): each ring or ring system (fused, bridged, spiro) is one node, rings joined by a bond stay separate nodes,:14911), every acyclic heavy atom is one node; the condensed graph is a forest, so every path between two ring nodes is an unbranched skeleton with two terminal rings. Whether each ring system is an allowed amplificant is not checked: that only makes the screen answer True more often.

The label check of the program (rule id in validation/pin_spelling) is the general guard over every name; this screen keeps the substitutive producers of the drug lane from building a name the book would replace by a phane name.

orthonym.rules.linear_phane_screen.phane_may_be_pin(mol)#

True when a linear phane name may be the PIN (2)); fails closed (True) on error. Memoised per molecule object.