orthonym.rules.bridged_fused_pin.derived_parents#

Note

Internal API. Names and behaviour may change between releases.

Fused ring parents the Blue Book does not print, derived step by step by the rules: name -> DerivedParent (the derivation, OPSIN input name, OPSIN SMILES, OPSIN locants in SMILES atom order).

(the Blue Book): fused mancude systems “that have no accepted retained or

systematic name described in sections and are named by prefixing to the name of a component ring or ring system (the parent component) designations of the other component(s) (attached components)”. parent_table.BB_PARENTS holds the names the book prints; this table holds a name the book does not print but its rules give, one entry per skeleton a bridged fused PIN needs (user ruling D6, 2026-10-02: a second small table of rule-derived parents, each with a written derivation and an OPSIN 2.9.0 test of its structure and numbering; no general widening). The structure and the numbering are OPSIN 2.9.0’s own reading of the name (<name> -o extendedsmi, its $_AV locants), as for BB_PARENTS; the derivation below is what makes the name and its numbering the ones, and tests/unit/rules/test_bf_s4_derived_parents.py checks each step against the entry and reads every entry back with OPSIN.

‘[1]benzofuro[3,2-e]isoquinoline’ – the fused parent of the 4,5-epoxymorphinans (morphine, codeine, thebaine, nalbuphine,…; their bridged fused name is ‘4,12-methano[1]benzofuro[3,2-e]isoquinoline’). Rings, with the morphinan atom labels of

(the Blue Book): A = benzene (C1-C4, C11, C12), E = furan (O, C4, C12, C13,

C5), C = C5-C8, C14, C13, D = C9, C14, C13, C15, C16, N17 (C10, the methano bridge, is not part of the parent).

  1. Components. (:12137) “If there is a choice for selecting the parent component, the following criteria are considered, in order”: (a) (:12139) “a component containing at least one of the heteroatoms occurring earlier in the following order: N > F >… > O” – the nitrogen components are pyridine (D) and the retained isoquinoline (C + D; N17 is bonded to C9, which is bonded to the fusion atom C14, so the nitrogen is at the 2-position: isoquinoline, not quinoline); (b) (:12163) “a component containing the greater number of rings” – isoquinoline. The benzene ring A is fused only to the furan E, so A + E is one benzoheterocycle unit, (:13437) “Heterobicyclic compounds consisting of a heteromonocycle fused to a benzene ring in which the benzene ring is not part of a system having a retained name… are treated as a single component unit (a ‘benzoheterocycle’…). They may be treated as a parent component or an attached component”, named ‘1-benzofuran (PIN)’ (:11827).

  2. Prefix. (:11907) “Locants that describe structural features of components, such as positions of heteroatoms, are kept with the name of the component and are enclosed within square brackets”; the book’s ‘[1]benzopyrano[2,3-c]pyrrole (PIN)’ (:12157) spells a benzoheterocycle prefix so: ‘[1]benzofuro’. No elision of the final ‘o’ (Note:11909).

  3. Descriptor. (:11911) “each peripheral side of the parent component… using the italic letters a, b, c, etc., beginning with a for the side numbered ‘1,2’, b for ‘2,3’ etc….. These numbers are chosen to be as low as is consistent with the numbering of the compound and their order conforms to the direction of lettering of the parent component”. Isoquinoline 1 (C9), 2 (N17), 3 (C16), 4 (C15), 4a (C13), 5 (C5), 6, 7, 8 (C6, C7, C8), 8a (C14): sides a 1-2, b 2-3, c 3-4, d 4-4a, e 4a-5. The furan is fused on C13-C5 = side e; 1-benzofuran’s C3 lies on 4a and its C2 on 5, so in the direction of lettering (4a -> 5) the attached locants are ‘3,2’: ‘[3,2-e]’. The attached locants 3 and 2 are nonfusion atoms of 1-benzofuran, and no locant of the parent component is cited: side e (4a-5) is a peripheral side of isoquinoline, lettered as:11911 letters “each peripheral side of the parent component (including sides whose locants are distinguished by letters, for example, 2a,3a)”. The fusion atom C13 (isoquinoline 4a) then carries four ring bonds, as naphthalene 8a does in ‘naphtho[1,8a-b]azirine (PIN)’,:14007,:14011); the book prints another fused PIN with such an atom, ‘cyclopenta[1,2-b:5,1-b’]difuran (PIN)’ (:13401).

  4. Orientation. (a) (:12083) “maximum number of rings in a horizontal row” with “vertical common bonds… always those furthest apart” (:12085): ring C cannot be the middle of a row (its two fusion bonds, to E and to D, share C13); the furan E can (its two fusion bonds are not adjacent), so A-E-C is the row (3 rings, the maximum). (b) (:12093) “maximum number of rings in upper right quadrant”: D is fused on the C13-C14 side of C next to the C/E bond, so with C at the right end and D above the row D lies in the upper right quadrant; the mirror images put D in the upper left or below. One orientation.

  5. Numbering. (:12501) “The numbering of peripheral atoms in the preferred orientation starts from the uppermost ring… from the nonfused atom most counterclockwise in the ring selected and proceeds in a clockwise direction around the system, including fusion heteroatoms but not fusion carbon atoms. Each fusion carbon atom is given the same number as the immediately preceding nonfusion skeletal atom, modified by a Roman letter”. The uppermost ring is D; clockwise from C13 its nonfusion atoms are C15, C16, N17, C9: 1, 2, 3, 4; then 4a (C14), 5, 6, 7 (C8, C7, C6), 7a (C5), 8 (O), 8a (C4), 9, 10, 11 (C3, C2, C1), 12 (C11), 12a (C12), 12b (C13). Heteroatoms at 3 and 8. OPSIN 2.9.0 numbers the name the same way (the entry’s locants are its $_AV output).

  6. Bridges on this parent. (a) (:14261) “contain the maximum number of rings”, (b) (:14271) “include the maximum number of skeletal atoms”: removing C10 leaves this 17-atom four-ring parent; removing -CH2-CH2-N< (C15, C16, N17) leaves phenanthro[4,5-bcd]furan (15 atoms) and loses (b); removing the oxygen leaves rings B, C, D sharing the bond C13-C14, not a fused parent. (:14181) bridge locants in numerical order: C10 joins 4 (C9) and 12 (C11): ‘4,12-methano’; (:14403) “Bridge atoms are numbered continuing from the highest locant of the fused ring system”: C10 is 13.

class orthonym.rules.bridged_fused_pin.derived_parents.DerivedParent(derivation, opsin_name, smiles, locants)#

Bases: NamedTuple

derivation: Tuple[Tuple[str, int], ...]#

(step, the Blue Book line) for each step of the module docstring’s derivation

opsin_name: str#

Alias for field number 1

smiles: str#

Alias for field number 2

locants: Tuple[str, ...]#

Alias for field number 3

orthonym.rules.bridged_fused_pin.derived_parents.DERIVED_PARENTS: Dict[str, DerivedParent] = {'[1]benzofuro[3,2-e]isoquinoline': ((('P-25.3.2.4 (a) nitrogen component', 12139), ('P-25.3.2.4 (b) more rings: isoquinoline', 12163), ('P-25.3.5 benzoheterocycle unit 1-benzofuran', 13437), ('P-25.3.1.3 component locants in square brackets', 11907), ('P-25.3.1.3 side letters and attached locants', 11911), ('P-25.3.8.4 a four-bonded fusion atom: naphtho[1,8a-b]azirine (PIN)', 14011), ('P-25.3.2.3.3 (a) rings in a horizontal row', 12083), ('P-25.3.2.3.3 (b) rings in the upper right quadrant', 12093), ('P-25.3.3.1.1 peripheral numbering', 12501)), '1H-[1]benzofuro[3,2-e]isoquinoline', 'C1C=NC=C2C=CC=C3C12C1=C(O3)C=CC=C1', ('1', '2', '3', '4', '4a', '5', '6', '7', '7a', '12b', '12a', '8a', '8', '9', '10', '11', '12')), 'cyclopenta[a]phenanthrene': ((('P-25.3.2.4 (b) more rings: phenanthrene is the parent component', 12163), ('P-25.3.2.2.1 monocyclic hydrocarbon prefix cyclopenta', 12000), ('P-25.3.1.3 side letter of the attached component', 11911), ('P-25.3.3 traditional numbering retained', 12493)), 'cyclopenta[a]phenanthrene', 'C1=CC=CC2=CC=C3C=4CC=CC4C=CC3=C12', ('1', '2', '3', '4', '5', '6', '7', '8', '14', '15', '16', '17', '13', '12', '11', '9', '10'))}#

name (indicated hydrogen dropped) -> DerivedParent