Clarkson, R. G. published the artcileSpirans with four aromatic radicals on the spiro carbon atom, Product Details of C25H16O, the publication is Journal of the American Chemical Society (1930), 2881-91, database is CAplus.
2-NCC6H4Ph, b43 202-4°, m. 35-6°, with PhMgBr gives 76% of 2-PhC6H4Bz, reduced by Mg-MgI2 to 9-phenyl-fluorene (25% yield) and gives with PhMgBr 63% of 2-phenyltriphenylcarbinol, m. 87-8°; it can be distilled with steam only if every trace of acid is previously removed. Attempts to prepare the chloride, even with AcCl at 0°, gives 9,9-diphenylfluorene. 2,3′,3”-Triphenyltriphenylcarbinol, from 3-BrC6H4Ph and 2-PhC6H4CO2Et, could not be crystallized; heating with AcOH containing a little concentrated H2SO4 gives 9,9-di[3-biphenyl]-fluorene, m. 190-1°. 2-IMgC6H4Ph and fluorenone give 70% of 9-[2-biphenyl]-9-fluorenol, m. 160-70°, crystallizes unchanged from; AcOH; AcOH containing a trace of HCl or I gives 9,9′-spirobifluorene, C26H16, m. AcCl in C6H6 gives the same compound; it is not affected by Zn in AcOH and does not add Br. 2-Iododiphenyl ether, from the 2-NO2 derivative by reduction and the Sandmeyer reaction, b22 198-202°. m. 54-6°; the Grignard reagent with fluorenone gives 9-[2-phenoxyphenyl]-9-fluorenol, slightly brown, m. 154°; with AcCl in AcOH this yields spiro-9-fluorene-9′-xanthene (I), m. 212-3°. A definite proof of the course of the condensation reaction is afforded by the synthesis of I from xanthone. 2-IMgC6H4Ph and xanthone give 9-[2-biphenyl-9-xanthenol, isolated as the mol. compound with xanthone; warming this with AcOH gives I. 2-Iodo-4′-methyldiphenyl ether, b34, 210-5°, m. 41° (74% yield from the NO2 derivative); the Grignard reagent with 2-bromofluorenone gives 9-[2-phenyl p-tolyl ether)-6-bromo-9-fluorenol, pale yellow, m. 175°; heating with glacial AcOH containing a little HCl gives spiro-9-[2-bromofluorene]-9′[-[2′-methylxanthene], m. 201°; the Me group could not be oxidized without destroying the spiran linkage. 2-lMgC6H4Ph and xanthone give 9-[2-phenoxyphenyl]-9-xanthenol, m. 136-7°; heating with AcOH 3 hrs. gives 9,9′-spirobixanthene, m. 283-4°; no evidence of salt formation was observed with dry HBr or HClO4. Reduction of 2-BrC6H4Bz with Zn-Hg gives 50% of 2-bromodiphenylmethane (II), b22 192-8°, does not solidify at 0°; the Grignard reagent with fluorenone gives 9-[2-benzylphenyl]-9-fluorenol, m. 132-3°; AcOH-HCl gives spiro-9-fluorene-9′-[9,10-dihydroanthracene, m. 207°. II and xanthone give 9-[2-benzylphenyl]-9-xanthenol, m. 146°; AcCl and AcOH give spiro-9-xanthene-9′-[9,10-dihydroanthracene], m. 257-9° (corrected). 2-BrC6H4CHPh2 yields a Grignard reagent after 24 hrs. boiling in Et2O-PhMe which gives with fluorenone 51% of 9-[2-benzohydrylphenyl]-9-fluorenol, m. 192°; AcOH-HCl transforms this into spiro-9-fluorene-9′-[10-Phenyl-9,10-dihydroanthracene), m. 267-8° (corrected), 9-[2-Benzohydrylphenyl]-9-xanthenol forms a mol. complex with xanthone, m. 200-5° decompn,); AcOH-HCl gives spiro-9-xanthene-9′-[10-phenyl-9,10-dihydroanthracene], m. 334-5° (corrected). [2-IMg-C6H4Ph and 10,10′-diphenylanthrone gives 55% of 9-[2-biphenyl]-10,10 diphenyl 9,10-dihydro-9-anthranol slightly yellow, m. 231-4° (decomposition); boiling AcOH gives quant. spiro-9-fluorene-9′-[10,10-diphenyl-9,10-dihydroanthracene), m. 363-4° (corrected). 2-IMg-C6H4OPh and diphenylanthrone give 74% of 9-[2-phenoxyphenyl]-10,10-diphenyl-9,10-dihydro-9-anthranol, m. 270-8° (corrected); AcOH gives quant. spiro-9-xanthene-9′-[10,10-diphenyl-9,10-dihydroanthracene], m. 377-80° (corrected). 2-IMgC6H4Ph and anthraquinone gives 25% of 9,10-di-[2-biphenyl]anthraquinol, m. 353-5° (corrected, decomposition); heating with AcOH-AcCl 4 hrs. gives quant. dispiro-9,9′-difluorene-9”,9”’-[9,10-di-hydroanthracene], m. 471-4° (corrected). 9,10-Di[2-phenoxyphenyl]anthraquinol, m. 351-3° (corrected, decomposition) (47% yield; heating with AcOH-H2SO4 8 hrs. on the steam bath gives 70% of dispiro-9,9′-dixanthene-9”,9”’-(9,10-dihydroanthracene), m. 487-90° (corrected). 2-IMgC6H4Ph and acenaphthoquinone give 32% of 7,8-di[2-biphenyl]acenaphthodiol, slightly yellow, m. 168°; AcOH-HCl does not give the expected dispiran but the pinacolin, C36H24O, m. 265-7° (corrected); hydrolysis of the latter with EtOH-KOH gives an acid, m. 252-4°(corrected). All the spirans are characterized by unusually high m. ps. and by extremely low insolubility
Journal of the American Chemical Society published new progress about 159-62-6. 159-62-6 belongs to naphthyridine, auxiliary class Other Aromatic Heterocyclic,Spiro, name is Spiro[fluorene-9,9′-xanthene], and the molecular formula is C25H16O, Product Details of C25H16O.
Referemce:
https://en.wikipedia.org/wiki/1,8-Naphthyridine,
1,8-Naphthyridine | C8H6N2 – PubChem