New near-IR-absorbing dyes were synthesized by condensation of the dicyanovinyl derivative of 1-acetyl-3-oxo-2,3-dihydroindole with nitroso compounds. The resulting products were found to be mixtures (ca. 9:1) of the (E)- and (Z)-isomers. The more bathochromic (E)-form could be converted into the (Z)-form by heating in methanol. At higher temperature new cyclization products were obtained. A mechanism of the isomerisation and cyclization is proposed

Adam, Jean-Marie

Sutter, Peter

Winkler, Tammo

English

CHIMIA

12. INTERNATIONALES FARBENSYMPOSIUM 505CHIMIA 48 (1994) Nr. II (Novemher)E. I O. 80.60.40.2o300 500 700nmE. Io300 500 700nmFigure. UVNIS Spectra in CHCf]" Left: 5 (absorption, fluorescence and solid-state fluorescence); right 4b (absorption and fluorescence).of 4 exhibit an intense solid-state fluores-cence.2.2. Peryleneamidineimides 8 or 9Many properties of 2 can be controlledby the substituents R, but not the UVNISspectra in solution [4] because of nodes inthe orbitals HOMO and LUMO at the N-atoms [5]. On the other hand, little isachieved by altering the basic chromophoreof 2. A possibility of shifting the UVNISspectra is an exchange of carbonyl groupsof the imide structure 3 by the related iminogroup. This has been done in a precedingwork [6] for one carbonyl group of eachimino ring. A bathochromic shift was ob-tained, but the fluorescence quantum yieldswent down to 60% or even lower.A more moderate altering of thechromophore of 2 is the exchange of onesingle carbonyl group to an imino group[7]. This can be attained by a partial alka-line saponification of 2 to 7 and a conden-sation of 7 with diamines to amidineim-ides like 8 or 9. These are intensely orangeto red fluorescing photostabe dyes.[I] See e.g. H. Zollinger, 'Color Chemistry', 1stedn., VCH Verlagsgemeinschaft, Weinheim,1987.[2] H. Langhals, Heterocycles, in press.[3] H. Langhals, S. Grundner, Chern. Ber. 1986,] ]9,2373.[4] A. Rademacher, S. Markle, H. Langhals,Chern. Ber. 1982, /15,2927.[5] H. Langhals, S. Demmig, H. Huber, Spectro-chirn. Acta, Part A 1988, 44, I 189.[6] 1. Lukae, H. Langhals, Chern.Ber. 1983,//6,3524.[7] H. Langhals, S. Sprenger, M.-T. Brandherm,Chern. Ber., in press.Chimia 48 (/994) 505-507© Neue Schweizerische Chemische Gesellschaft/SSN 0009-4293Malononitrile, a Synthetic Toolfor New Chromophoric SystemsJean-Marie Adam*, Peter Sutter, and Tammo WinklerAbstract. New near-IR-absorbing dyes were synthesized by condensation of thedicyanovinyl derivative of l-acetyl-3-oxo-2,3-dihydroindole with nitroso compounds.The resulting products were found to be mixtures (ca. 9: 1) of the (E)- and (Z)-isomers.The more bathochromic (E)-form could be converted into the (Z)-form by heating inmethanol. At higher temperature new cyclization products were obtained. A mecha-nism of the isomerisation and cyclization is proposed.1. IntroductionAt the present time, there is currentinterest in the development of near-IRabsorbing dyes for use e.g. in diode-laseroptical storage systems. Several investi-gations have been reported on the synthe-sis and properties of IR dyes suitable forelectro-optical applications [1]. Methinedyes are widely applied in this area be-cause their absorption bands can be easilyshifted into the longwave region by thesuitable choice of dye end-groups or byextending the methine chain. In this re-*Correspondence: Dr. J.M. AdamTextile Dyes DivisionCiba-Geigy Ltd.CH-4002 Basel12. INTERNATIONALES FARBENSYMPOSIUM 505CHIMIA 48 (1994) Nr. II (Novemher)E. I O. 80.60.40.2o300 500 700nmE. Io300 500 700nmFigure. UVNIS Spectra in CHCf]" Left: 5 (absorption, fluorescence and solid-state fluorescence); right 4b (absorption and fluorescence).of 4 exhibit an intense solid-state fluores-cence.2.2. Peryleneamidineimides 8 or 9Many properties of 2 can be controlledby the substituents R, but not the UVNISspectra in solution [4] because of nodes inthe orbitals HOMO and LUMO at the N-atoms [5]. On the other hand, little isachieved by altering the basic chromophoreof 2. A possibility of shifting the UVNISspectra is an exchange of carbonyl groupsof the imide structure 3 by the related iminogroup. This has been done in a precedingwork [6] for one carbonyl group of eachimino ring. A bathochromic shift was ob-tained, but the fluorescence quantum yieldswent down to 60% or even lower.A more moderate altering of thechromophore of 2 is the exchange of onesingle carbonyl group to an imino group[7]. This can be attained by a partial alka-line saponification of 2 to 7 and a conden-sation of 7 with diamines to amidineim-ides like 8 or 9. These are intensely orangeto red fluorescing photostabe dyes.[I] See e.g. H. Zollinger, 'Color Chemistry', 1stedn., VCH Verlagsgemeinschaft, Weinheim,1987.[2] H. Langhals, Heterocycles, in press.[3] H. Langhals, S. Grundner, Chern. Ber. 1986,] ]9,2373.[4] A. Rademacher, S. Markle, H. Langhals,Chern. Ber. 1982, /15,2927.[5] H. Langhals, S. Demmig, H. Huber, Spectro-chirn. Acta, Part A 1988, 44, I 189.[6] 1. Lukae, H. Langhals, Chern.Ber. 1983,//6,3524.[7] H. Langhals, S. Sprenger, M.-T. Brandherm,Chern. Ber., in press.Chimia 48 (/994) 505-507© Neue Schweizerische Chemische Gesellschaft/SSN 0009-4293Malononitrile, a Synthetic Toolfor New Chromophoric SystemsJean-Marie Adam*, Peter Sutter, and Tammo WinklerAbstract. New near-IR-absorbing dyes were synthesized by condensation of thedicyanovinyl derivative of l-acetyl-3-oxo-2,3-dihydroindole with nitroso compounds.The resulting products were found to be mixtures (ca. 9: 1) of the (E)- and (Z)-isomers.The more bathochromic (E)-form could be converted into the (Z)-form by heating inmethanol. At higher temperature new cyclization products were obtained. A mecha-nism of the isomerisation and cyclization is proposed.1. IntroductionAt the present time, there is currentinterest in the development of near-IRabsorbing dyes for use e.g. in diode-laseroptical storage systems. Several investi-gations have been reported on the synthe-sis and properties of IR dyes suitable forelectro-optical applications [1]. Methinedyes are widely applied in this area be-cause their absorption bands can be easilyshifted into the longwave region by thesuitable choice of dye end-groups or byextending the methine chain. In this re-*Correspondence: Dr. J.M. AdamTextile Dyes DivisionCiba-Geigy Ltd.CH-4002 Basel12. INTERNA TIONALES FARBENSYMPOSIUM 506CHIMIA 48 (199~) Nr. II (November)Reaction of N-acetylisatin (1) withmalononitrile gives l-acetyl-3-(dicyano-methylene )-1 ,3-dihydro-2H-indol-2-one(4) (Scheme 1), which is known to reactwith aromatic amines via ring expansionor cyanide exchange, depending upon thereaction conditions [4]. In any case, noreaction with the carbonyl group leadingto 5 could be observed. We decided toinvestigate the more promising startingmateriall-acetyl-3-oxo-2,3-dihydroindole(2), readily synthesized from anthranilicacid by known methods [5][6].Our first aims were to prepare l-acety 1-3-dicyanometh yIidene- 2 ,3-d ihydroi ndo 1e(6) and to attempt the reaction of thisintermediate with various aromatic nitrosoderivatives 7 to give condensation adducts5. A full description of these dyes is givenin [7]. Reaction of2 with a large excess ofmalononitrile and piperidine as a catalystgave quantitatively the dicyanovinyl de-rivative 6. The condensation of 6 with thenitroso derivative 8 was achieved smooth-ly in acetic anhydride and afforded 9 as amixture (ca. 9: 1) of the (£)- and (2)-isomers (Scheme 2), which could be sepa-rated by chromatography. By heating inmethanol, (£)-9 could be readily convert-ed into (2)-9, the mechanism of this isom-erisation is discussed in Scheme 5. Thesomewhat longer wavelength absorptionof (£)-9, (A.max (CHCI3) = 736 nm), rela-tive to (Z)-9, (A111ax (CHCb) = 693 nm),reflects the larger steric crowding in theformer structure, inducing a torsion of thecentral C=N unit.2. Experimental Resultsgard the dicyanovinyl group is of particu-lar interest, because its strong electron-acceptor property confers chromophoricand highly efficient auxo-chromic charac-ter and can be easily introduced as dyeend-group by a Knoevenagel reaction of acarbonyl function with malononitrile. Al-though some dicyanovinyl derivatives ofmethine dyes based on indan-I,3-dionehave already been synthesized [2], lessattention has been given to other ana-logues such as N-acetylisatin (1) and 1-acetyl-3-oxo-2,3-dihydroindole (2) andnothing has been published about the chem-ical behaviour of these dicyanovinyl de-rivatives.The purpose of this paper is to describethe synthesis and reactivity of these newnear-IR absorbing compounds as well astheir visible absorption properties, as anextension of our previous studies on thefunctionalization of 2-arylindolenin-3-ones (3) with malononitrile [3].53H3C N-C2Hs'''C~CH39 - (Z)A.(CHCI3) : 693 nm~-NH2/~cx}NC CN~ I !. -N0... N \.\ RAc+NC"IJrCNV-N>\Ac42cx}NC; CNI 00... N\AcoOJ\Ac6NC~rCNV-N>\Ac6219 - (E)A.(CHCI3) : 736 nm1oOJ\Aco~O~NF\Aco~OVNF\AcoSNCC~ I !. -N0... N\AcScheme 2Scheme 112. INTERNATIONALES FARBENSYMPOSIUM 507CHIMIA 48 (199~) Nr. II (Nm'cmher)3. DiscussionThe cyc1ization giving 11 (way b) canbe rationalized as a concerted mechanism[1] Z. Yoshida, T. Kitao, in 'Chemistry ofFunc-tional Dyes', Eds. Z. Yoshida and T. Kitao,Mita Press, Tokyo, 1989.[2] K.A. Bello, L. Cheng, 1. Griffiths, J. Chem.Soc .. Perkin Trans. 2 1987. 815.[3] 1.M. Adam, T. Winkler, He/v. Chim. Acta1984, 67, 2186.[4] M.1. Younes, Liebigs Ann. Chern. 1990, 703.[5] S.J. Holt, A.E. Kellie, D.G. O'Sullivan, P.W.Sadler, J. Chem. Soc. 1958, 1217.[6] S.J. Holt, P.W. Sadler, Proc. R. Soc. London[Ser.] B 1958, 148,481.[7] Ciba-Geigy, Eur. Pat. 462928 (19.6.1990).[8] Ciba-Geigy, German Pat. 4215654 (16.5.1991); Ciba-Geigy, German Pat. 4215718(16.5.1991).involving a retro-Knoevenagel reactionwith elimination of malononitrile afford-ing the corresponding ketone, which re-acts with the amine resulting from thehydrolysis of the propionylamino group.The dramatic red shiftof11, (A.max(CHCI3)= 476 nm), relative to 9, reflects the loss ofthe powerful electron acceptor, leading toa system with a very low chromophoriccharacter.To explain the cyclisation leading tothe main product 10 (way a), we believethat the reactive intermediate is probablythe tautomeric structure 9a (Scheme 4),which cyclizes spontaneously into 12. Thearomatization occurs through eliminationof cyanhydric acid. The visible absorptionband of 10 in CHCb exhibits a maximumat562 nm. This proposed mechanism couldexplain the conversion of (E)-9 into (2)-9in methanol (Scheme 5). Solvents withhigh dielectric constant such as methanolstabilize the separation of the electroniccharges in 9a, facilitating a rotation aboutthe central C-N bond leading to 9b.CH3.,,\ CH310A.(CHCJ3): 562 nrnQxNYY~1~':"j'l "N~Ac CH311A.(CHCI3): 476 nrnthem cyclized quickly [8], giving a mix-ture of two new compounds 10 (mainproduct) and 11 (trace) the structures ofwhich were proven by analytical and phys-ical means (Scheme 3). It is obvious thatonly the (E)-isomer has the right geometryto be the precursor of the cyclization prod-ucts.8,D~~NScheme 3Although analogues of 9, based on 3-dicyanovinylindan-I-one and 3-dicyanovi-nyl-l, l-dioxobenzo[b ]thiophene have al-ready been synthesized [2], the formationof isomers have not been reported by theauthors. These products have a Amax below700 nm, which is significantly lessbathochromic than (E)-9.The NMR spectra did not enable one toclearly distinguish between the (E)- and(2)-isomers; nevertheless, their structurescould be established indirectly by chemi-cal methods. Surprisingly, we found that,on heating both isomers in DMF, one ofScheme 4 Scheme 5cr):NCev I I _N~'" N\ 'I '\Ac9-(Z) N-/9 - (E)9a\ +roNC-C ~-v ~ KI N~ N\Ac109\6&NCCNqN-I ~;;?'I -N~ N\Ac-HCN12I~v-1.--';roNC-:;U;;?' ~ /,I N~ N\Ac9a

Malononitrile, a Synthetic Tool for New Chromophoric Systems

https://www.chimia.ch/chimia/article/download/1994_505/1748

Malononitrile, a Synthetic Tool for New Chromophoric Systems

Abstract

Similar works

Full text

Available Versions

CHIMIA