Appendix 2

Note a

1	Phenoxazine (X = O)		(10H-form shown)
2	Phenothiazine (X = S)
3	Phenoselenazine (X = Se)
4	Phenotellurazine (X = Te)
5	Phenophosphazinine (X' = P)		Note b
6	Phenarsazinine (X' = As)			Note c
7	Phenomercurazine (5H form shown)		Note d
8	Phenazine (X' = N)		See 5 and 6
9	1,7-Phenanthroline
10	1,8-Phenanthroline
11	1,9-Phenanthroline
12	1,10-Phenanthroline		1,7-isomer shown
13	2,7-Phenanthroline
14	2,8-Phenanthroline		Note. One nitrogen atom
15	2,9-Phenanthroline		in each of the two
16	3,7-Phenanthroline		terminal rings,
17	3,8-Phenanthroline		see FR-2.2.4
18	4,7-Phenanthroline
19	Perimidine (1H-form shown)
20	Acridine		Note e
21	Phenanthridine Note f
22	Carbazole (9H-form shown)		Note e
23	Pteridine
24	Cinnoline
25	Quinazoline
26	Quinoxaline
27	1,5-Naphthyridine		1,5-isomer shown
28	1,6-Naphthyridine		Note. One nitrogen
29	1,7-Naphthyridine		atom in each ring.
30	1,8-Naphthyridine		see FR-2.2.4
31	Phthalazine
32	2,6-Naphthyridine		see 27-30
33	2,7-Naphthyridine		see 27-30
34	Quinoline		Note g
35	Isoquinoline		Note g
36	Quinolizine (2H-form shown)		Note g
37	Purine (7H-form shown)		Note e
38	Indazole (1H-form shown)
39	Indole (1H-form shown)
40	Isoindole (2H-form shown)
41	Indolizine
42	Pyrrolizine (1H-form shown)

43	Seven-membered heterocyclic ring or larger with at least one nitrogen atom, e.g. azepine.
44	Six-membered heterocyclic ring with at least three heteroatoms including at least one nitrogen atom, e.g. 1,3,5-oxadiazine.
45	Six-membered heterocyclic ring with one nitrogen atom and a different heteroatom, e.g. 1,2-thiazine.

46	Pyridazine
47	Pyrimidine
48	Pyrazine
49	Pyridine

50	Five-membered heterocyclic ring with at least three heteroatoms, including at least one nitrogen atom, e.g. 1,2,5-oxadiazole (formerly called furazan).
51	Five-membered heterocyclic ring with one nitrogen atom and a different heteroatom e.g. 1,2-oxazole. Note h

52	Pyrazole (1H-form shown)
53	Imidazole (1H-form shown)
54	Pyrrole (1H-form shown)

55	Three- or four-membered heterocyclic ring with at least one nitrogen atom e.g. azirene.
56	Heterocyclic ring with halogen but no nitrogen atom e.g. 15-1,2-iodoxole

57	Phenoxathiine (X = S)
58	Phenoxaselenine (X = Se)
59	Phenoxatellurine (X = Te)
60	Phenoxaphosphinine (X = PH)		Note i
61	Phenoxarsinine (X = AsH)		Note j
62	Phenoxastibinine (X = SbH)		Note k
63	Oxanthrene (X = O)		Note l
64	Xanthene (9H-form shown)		Note e
65	Chromene (2H-form shown)		Note m
66	Isochromene (1H-form shown)		Note n
Note o

67	Seven-membered heterocyclic; ring or larger with at least one oxygen atom (no nitrogen atom; see 43) e.g. oxepine.
68	Six-membered heterocyclic ring with two or more heteroatoms at least one of which is oxygen (no nitrogen atom; see 44, 45) e.g. 1,4-dioxine

69

Pyran (2H-form shown)

70	Five-membered heterocyclic ring with two or more heteroatoms at least one of which is oxygen (no nitrogen atom; see 50-51) e.g. 1,3-dioxole.

71

Furan

72	Three or four-membered heterocyclic ring with at least one oxygen atom (no nitrogen atom; see 55) e.g. oxirene.

73	Phenothiarsinine see 57-63, X = AsH, S instead of O Note p
74	Thianthrene see 57-63, X = S, S instead of O
75	Thioxanthene see 64, S instead of O Note e
76	Thiochromene see 65, S instead of O Note m
77	Isothiochromene see 66, S instead of O Note n
78	Heteromonocyclic ring with at least one sulfur atom (no nitrogen or oxygen atoms). The trivial names thiophene (see 71, S instead of O) and thiopyran (see 69, S instead of O) are retained.
79	Selenanthrene see 57-63, X = Se, Se instead of O
80	Selenoxanthene see 64, Se instead of O Note e
81	Selenochromene see 65, Se instead of O Note m
82	Isoselenochromene see 66, Se instead of O Note n
83	Heteromonocyclic ring with at least one selenium atom (no N, O or S atoms) The trivial name selenophene (see 71, Se instead of O) is retained.
84	Telluranthrene see 57-63, X = Te, Te instead of O
85	Telluroxanthene see 64, Te instead of O Note e
86	Tellurochromene see 65, Te instead of O Note m
87	Isotellurochromene see 66, Te instead of O Note n
88	Heteromonocyclic ring with at least one tellurium atom (no N, O, S, or Se atoms). The trivial name tellurophene (see 71, Te instead of O) is retained.
89	Phosphanthrene see 5, 6, & 8, X' = P, P instead of N
90	Acridophosphine see 5, 6, & 8, X' = CH, P instead of N Note q
91	Phosphanthridine see 21, P instead of N
92	Phosphinoline see 34, P instead of N
93	Isophosphinoline see 35, P instead of N
94	Phosphinolizine, see 36, P instead of N
95	Phosphindole see 39, P instead of N
96	Isophosphindole see 40, P instead of N
97	Phosphindolizine, see 41, P instead of N
98	Heteromonocyclic ring with at least one phosphorus atom (no N, O, S, Se or Te atoms).
99	Arsanthrene see 5, 6, & 8, X' = As, As instead of N
100	Acridarsine see 5, 6, & 8, X' = CH, As instead of N Note q
101	Arsanthridine see 21, As instead of N
102	Arsinoline see 34, As instead of N
103	Isoarsinoline see 35, As instead of N
104	Arsinolizine, see 36, As instead of N
105	Arsindole see 39, As instead of N
106	Isoarsindole see 40, As instead of N
107	Arsindolizine, see 41, As instead of N
108	Heteromonocyclic ring with As, and Sb, Bi, Si, Ge, Sn, Pb, B, Hg as possible heteroatoms.
109	Silanthrene see 5, 6, & 8, X' = SiH, SiH instead of N
110	Boranthrene see 5, 6, & 8, X' = B, B instead of N)
111	Mercuranthrene see 57-63, X = Hg, Hg instead of O Note r

Notes.

a. CAS includes ten additional fusion parent components which have higher priority. In order of preference they are:

c. Formerly called phenoarsazine

d. Formerly called phenomercazine;CAS calls 2H-phenomercurazine (3,6-cyclohexadien-1-yl-2-ylidene-nitrilo-1,2-phenylene)mercury.

e. Non-standard numbering.

f. -Carboline (pyrido[3,4-b]indole) was abandoned as a fusion parent component in the 4th edition of section B (ref 3).

g. CAS retains the traditional order quinolizine preferred to quinoline, preferred to isoquinoline.

h. Isoxazole, oxazole, isothiazole, thiazole, isoselenazole, selenazole, isotellurazole and tellurazole are now named as Hantzsch-Widman heterocycles (1,2-oxazole, 1,3-oxazole, 1,2-thiazole, 1,3-thiazole etc.) but were formerly used as components. They are still used by CAS and Beilstein.

i. Formerly called phenoxaphosphine as used by CAS.

j. Formerly called phenoxarsine as used by CAS.

k. Formerly called phenoxantimonine as used by CAS.

l. Formerly called dibenzo[b,e][1,4]dioxine. CAS uses dibenzo[b,e][1,4]dioxin, Beilstein uses dibenzo[1,4]dioxine.

m. Called 1-benzopyran by CAS. Similarly CAS uses 1-benzothiopyran, 1-benzoselenin and 1-benzotellurin for the chalcogen analogues.

n. Called 2-benzopyran by CAS. Similarly CAS uses 2-benzothiopyran, 2-benzoselenin and 2-benzotellurin for the chalcogen analogues.

o. Benzofuran and isobenzofuran are no longer used as fusion parent components. CAS still uses both whereas Beilstein uses both for the unmodified ring system but only furan for further fusion.

p. Formerly called phenothiarsine.

q. Standard numbering [not as acridine (20)] (Ref 3a is in error on this point).

r. Formerly called phenomercurin or phenomercurine; CAS and Beilstein calls mercuranthrene cyclo-di--1,2-phenylenedimercury.

3. IUPAC Nomenclature of Organic Chemistry, Sections A and B, 1st edition, 1958; 2nd edition, 1966; 3rd edition (combined with section C), 1971; 4th edition (combined with sections C, D, E, F and H), 1979.

3a. A Guide to IUPAC Nomenclature of Organic Compounds, Recommendations 1993, Blackwell Scientific Publications, 1993.