orthonym.rules.ring_assembly_screen

Note

Internal API. Names and behaviour may change between releases.

Does this molecule join two identical ring systems by a bond?,; fail closed).

### **** DEFINITIONS (the Blue Book),:15542: “Two or more cyclic systems (single rings or fused systems, alicyclic von Baeyer systems, spiro systems, phane systems, fullerenes) that are directly joined to each other by single or double bonds are called ‘ring assemblies’ when the number of such direct ring junctions is one less than the number of cyclic systems involved.”;:15550: “Ring assemblies are composed of identical cyclic systems (rings or ring systems); assemblies of nonidentical cyclic systems (rings or ring systems) are not called ring assemblies for the purposes of organic nomenclature”. ### **** Ring assemblies with a single bond junction (:15560),:15569: “The name biphenyl is retained as 1,1’-biphenyl.”

Identity is that of the ring skeleton: ## **** UNSATURATION IN RING ASSEMBLIES COMPOSED OF MONOCYCLIC MANCUDE AND SATURATED RINGS (:24151),:24153: “When assemblies of otherwise identical rings contain both mancude and saturated rings, the use of hydro prefixes is preferred, except in the case of a two ring assembly consisting of one benzene ring and a cyclohexane ring.”;:24159 ‘1,2,3,4,5,6-hexahydro-2,2’-bipyridine (PIN)’ (not ‘2-(piperidin-2-yl)pyridine’);:24157 ‘cyclohexylbenzene (PIN)’. ### **** Ring assemblies composed of monocyclic components (:17077),:17079: “In biphenyl and polyphenyl assemblies, one benzene ring must remain in the assembly… Furthermore, when a modified ring assembly of two rings consists of a benzene ring and a cyclohexane ring substitutive nomenclature is preferred (see.”;:17083 ‘2,3-dihydro-1,1’-biphenyl (PIN)’ (not ‘(cyclohexa-1,3-dien-1-yl)benzene’). So a pyridine bonded to a piperidine, or a benzene bonded to a cyclohexene, is a ring assembly named with hydro prefixes; only the two-ring assembly of one benzene ring and one cyclohexane ring is named substitutively. The junction may be a ring nitrogen (****,:15593; ‘1,1’-bipyrrole (PIN)’:15603, ‘2H-1,2’-bipyridine (PIN)’ :15634), so a pyridine bonded to the nitrogen of a piperidine is one too (‘3,4,5,6-tetrahydro-2H-1,2’-bipyridine’).

A ring assembly is a parent of its own ((g) ring assembly,:19542) and has more rings than either of its components (“The senior ring or ring system has the greater number of rings”,:19461), so a principal characteristic group on one component is the suffix of the assembly: ‘(1P)-2’,5’-dimethoxy-6-nitro[1,1’-biphenyl]-2-carboxylic acid (PIN)’ ,:49805), and the book does not take the assembly apart into a phenyl prefix on a benzene ring (‘([1,1’-biphenyl]-4-yl)oxy (preferred prefix) (not 4-phenylphenoxy)’, :24607). A substitutive name such as ‘4-phenyl-N-(pyridin-2-yl)benzamide’ for N-(pyridin-2-yl)[1,1’-biphenyl]-4-carboxamide is therefore not the PIN.

The producers of the drug lane do not decide between an assembly parent and a component parent. They consult this screen, so that no name they build with one component as the parent is certified as the PIN. True means: the molecule holds two ring systems with the same skeleton joined by a bond, other than the one two-ring benzene + cyclohexane assembly of, or the screen could not tell (fail closed).

orthonym.rules.ring_assembly_screen.ring_system_key(mol, atoms)

The ring system’s skeleton: its elements and connectivity, every bond single and no aromatic flag (hydrogens, charges, isotopes and decorations ignored), as a canonical SMILES. The mancude and the saturated forms of one ring system share it (pyridine and piperidine, benzene and cyclohexene): the “otherwise identical rings” of (:24153).

orthonym.rules.ring_assembly_screen.ring_is_in_biphenyl_assembly(mol, ring_atoms)

True when the ring system that holds ring_atoms is joined, through a group of ring systems with the same skeleton (a ring assembly,:15542; the two-ring benzene + cyclohexane assembly of left out), to ANOTHER benzene ring: a biphenyl or polyphenyl assembly. On error True (fail closed).

This is the question a writer of a SINGLE-ring parent (benzene, name_substituted_ benzene) has to ask about its own parent ring: where the parent ring is one member of such an assembly, the assembly, which has more rings, is the senior parent:19461; ### **** Retained names:27665,:27722-27724 ‘4-methoxy-1,1’-biphenyl (PIN)… [not 1-methoxy-4-phenylbenzene; the biphenyl ring system is senior to a single benzene ring]’), and the single-ring name is not the PIN. An assembly elsewhere in the molecule, that does not hold the parent ring, does not change the parent. An assembly of a benzene ring with a partly saturated ring (hydro prefixes,:17077) is not this question and is left to the writers that decide it. Not memoised: the answer depends on the ring.

orthonym.rules.ring_assembly_screen.joins_identical_ring_systems(mol)

True when two ring systems of mol with the same skeleton are joined directly by a bond (a ring assembly,; mancude and saturated members alike,, unless the assembly is the two-ring benzene + cyclohexane one that names substitutively, or on error (fail closed). Memoised per molecule object.