Spiro-fluorenes

Photolysis of spiro[fluorene-9,3 -indazole] (384) to the tribenzopentalene (385) has been rationalized in terms of the initial formation of triplet diradical (386) (76JOC2120). The spiroindazole (387) behaves differently and on irradiation in THF is converted into the dimer (388) and the stable iV-ylide (389) (76CB2596). 

H-2, 2 -Spirodibenzo-1,3,2-dioxaphosphole synthesis, 1, 522 Spiro[fluorene-9,3 -indazole] photolysis, 5, 252... 

SCHEME 2.43 Synthesis of random PFs with spiro-fluorene moieties. (From Marsitzky, D., Murray, J., Scott, J.C., and Carter, K.R., Chem. Mater., 13, 4285, 2001.)... 

The yellow solution of l /H-2, 3 -6 tricarbomethoxy-spiro[fluorene-9,T-pyrrolo[l,2-6]pyridazine] in chloroform was irradiated, after flushing with argon,... 

Both enantiomers of 9,9 -spirobixanthene-l,l -diol have been obtained by resolution of the racemic product derived from 1-methoxyxanthone <06OBC4474> and spiro[fluorene-9,9 -xanthenes] 36 result from a one-pot reaction between fluorenone and phenol using an excess of MeS03H <06OL2787>. 

Several 2// -chromcnc derivatives exhibit photo-, thermo- or solvatochromic behavior in solution. Specific structural features of the substituted di-phcnylchro-menes CH1-CH4, the dimethyl chromenes CH5, and the spiro[fluorene-benzopyr-ans] SFB1 and SFB2 have been studied.75 77... 

S. Aldoshin, I. Chuev, O. Filipenko, J. L. Pozzo, V. Lokshin, and R. Guglielmetti, Structure and photochromic properties of spiro[fluorene-chromenes], Acta Crystallogr. Sect. C (in press). 

In some cases the indazole and spiroindazole route did not lead to isolable cycloproparenes. Thus, the attempted synthesis of a 1,1-diphenylbenzocyclopropene or 1-phenylbenzocyclo-propene-l-carbonitrile by this route resulted instead in isolation of fluorene derivatives. The photolysis or pyrolysis of spiro[fluorene-9,3 -3//-indazole] gave fluoradene (4b//-indeno-[l,2,3-y, ]fluorene) as the major product (80%). The cycloproparene, spiro[17/-bcnzocyclo-propene-l,9 -fluorene], although formed as a reaction intermediate, was not isolable. Similarly, the thermolysis and photolysis of 9,10-dihydrospiro[anthracene-9,3 -3 /f-indazole]-10-one gave spirocycloproparenes as (non-isolable) reactive intermediates. ... 

The yellow solution of spiro-fluorene-pyrrolo-pyridazine 8.2e in chloroform was irradiated (see procedure for 8.2d), after flushing with argon, in a 13 cm cuvet. The solution turned red-violet with the formation of the betaine form 8.2f. The color of the betaine 8.2f faded with a half life of t /2 = 4.95 s. 

Fig. 5.33. Graphical representation of an evaluation according to eq. (5.132) for the superimposed photochemical and thermal reaction of FH-2, 3 -dimethoxycabonyI-spiro-[fluorene-...

A very important characteristic that holds for all spiro-fluorene compounds discussed in this chapter is that they do not exhibit a long wavelength emission beyond 500 nm, which is usually found in poly(fluorene)s after annealing. This indicates the effective prevention of local aggregates. 

Blue organic light-emitting diode with improved color purity using 5-naphthyl-spiro[fluorene-7,9 -benzofluorene] was designed [36]. Novel spiro-type blue host... 

The full details of oxa-bis- and oxa-tris-a/ic-homobenzene syntheses, cw-aza-bis-and cis-aza-tris-a-homobenzene and cis-aza-tris-a-homotropilidene synthesis, and the decomposition of spiro[fluorene-9,3 -indazole] have become available, and there have been a number of routine applications of pyrazoline decomposition for cyclopropane synthesis. ... 

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