Indolines spiro

Scheme 12.68 Domino synthesis of indoline-spiro benzofurodiazepines.

Spiro-(indoline-isoxazolidines) 137, exhibiting interesting biological activities, were prepared in modest yields, by the cycloaddition reaction between ethyl (3-indolylidene)-acetate 135 and various substituted a,N-diphenylnitrones 136 under solvent-free conditions (Scheme 48). The reaction conducted under conventional heating in an oil bath did not proceed even after 20 h, especially when it was carried out without solvent [87]. 

The numbering of spiropyrans adopted throughout this review is indicated in Figure 1.2. The nomenclature of the spiropyran 1 is given as 1, 3, 3 -trimethyl-spiro[2H-l-benzopyran-2,2 -indoline] it is referred to as spiroindolinobenzopyran and abbreviated as BIPS. 

The absorption bands for both quinoid and dipolar structures have been calculated by the PPP method.2,12 The calculations for a more simplified model of the colored form of some spirobenzopyrans using the normal parameters are shown in Table 2.12 In this case, the spiro carbon in the indoline moiety is ignored in the 7i-electron system, and the quinoid structure is assumed. 

Indolines, benzoxazole, and benzothiazole are possible as 2-methylene heterocycles. The number of known spirooxazine derivatives is much less than for the spiropyrans. This may be partly due to lack of many substituted o-nitrosonaphthols and partly due to lack of sufficient stability of spiro-oxazines. The structures of parent spirooxazines and the Xmax of their photomerocyanine forms are listed in Table 5. The Xmax of the colored forms of compounds 41-43 are not described in the literature. 

A number of novel spiro heterocycles, including the triazepinethione 146 have been derived from 3-hydroxy-3-(2-oxocyclohexyl)indolin-2-one 145 by condensation with active methylene compounds <00SC1257>. A condensation process was also used to prepare tricyclic triazepinones related to the non-nucleoside reverse transcriptase inhibitor nevirapine <00JHC1539>. 

Distribution of spin density in the framework of trianion-radicals allows determining whether or not there is some conjugation between substituents at different sites. For example, reduction of dinitro spiro(indoline-benzopyran) with potassium tert-butoxide in DMSO proceeds according to Scheme 1.40 (Alberti et al. 1995). 

Two permanent merocyanines have been reported for the spiro-oxazines [85]. These were NOSH heteroanellated by imidazo [l,2-a]pyridine and imidazo [l,2-a]pyrimadine. Several tests have been conducted to determine the nature of these species. H -NMR data show that the indoline nitrogen is not highly charged and the crystal structure indicates that the ground state is essentially the quinoidal form. The most stable form was found to be the TTC isomeric form by x-ray analysis. The dipole moment of these permanent spiro-oxazine merocyanines was around 3.84 D, which is much lower than the values reported for spiropyran merocyanines. 

Schneider et al. [63] investigated the photochemistry of the spiro-oxazine merocyanines pumping and probing at 570 nm in acetonitrile. The found that the solution bleached within the <5-psec pulse duration. The bleached state recovered with at least a biexponential behavior, and from their fluorescence decay measurements, three exponentials were required to fit the decay. They attribute these findings to the possibility of three merocyanine isomers that are in equilibrium. Their compounds feature geminal ethyl groups on the indoline moieties and this may influence the system as compared to NOSIl. 

The spiro compound 15 is obtained in excellent yield by the cycloaddition of 3-(4-fluorophenylimino)indolin-2-one with mercaptopropionic acid under microwave irradiation <2003SUL201>. Treatment under basic conditions of 2,3-dihalopropylamines with carbon disulfide results in the formation of two isomeric products 5-halotetrahydro-l,3-thiazine-2-thione 204 and 5-(halomethyl)thiazolidine-2-thione 205 <2002CHE1533>. 

Spiro 1 - methylsulfony 1-3//-indoline -3,2 -[3, 5 -di(ethoxycarbonyl)-4 -methyl-2 //-pyrrole] (64) underwent molecular rearrangement with 100% H3PO3,60% H2SO4, or by heating at 200° to 1,3-di(ethoxycarbonyl)-2-methyl-6-methylsulfonyl-4,5-dihydropyrrolo[ 1,2-c]quinazoline (65)... 

A spiro indoline (347) has been isolated from the reaction of the quaternized derivative of 5-methoxy-l-methyl-3-(2-dimethylaminoethyl)indole with lithium in liquid ammonia in the absence of a proton donor (68TL81). The product presumably arises from the rapid sequential addition of two electrons to generate the dianion of the tryptamine, which facilitates the nucleophilic displacement of trimethylamine. Reduction in the presence of methanol produces the 4,7-dihydrotryptamine (see Section 3.05.1.5). 

Dandia, A., Saha, M. and Taneja, H., Improved one-pot synthesis of 3-spiro indolines under microwave irradiation, Phosphorus, Sulfur Silicon, 1998, 139, 77-85. 

As shown by means of electrochemical ESR spectroscopic methods and confirmed by ab initio calculations (Alberti et al. 1995), the first electron is accommodated in the more accessible nitrobenzopyran moiety. Next, the second electron fits into the nitroindoline moiety in virtually the same orbital that in the anion radical of mon<9-nitro-spiro(indoline-benzopyran), is occupied by the unpaired electron. The mono-nitro anion radical is also formed by the aforementioned reaction with terf-BuOK in DMSO, Scheme 1-63. 

As to the third step of the step-wise one-electron reduction of t//-nilro-spiro(indoline-benzopyran), the third extra electron is again accommodated into the nitrobenzopyran unit without affecting the spin density distribution on the opposite fragment, which therefore remains essentially identical to that of the anion radical of mono-nitro-spiro(indoline-ben-zopyran). Hence, the spiro-nodal carbon atom prevents conjugate interactions between the indoline and benzopyran moieties. 

Fedorova, O.A., Gromov, S.P., Pershina, Y.V., Sergeev, S.S., Strokach, Y.P., Barachevsky, V.A., Alfimov, M.V., Pepe, G., Samat, A., Guglielmetti, R. (2000) Novel azacrown ether-containing spiro[indoline-2,3,-naphthoxazines] design, synthesis and cation-dependent photochromism, J. Chem. Soc., Perkin Trans. 2, 563-571. 

Fig. 5 Smart UV-responsive coating on silica nanoparticles with PNIPAM brushes functionalized with FRET donors, 4-(2-acryloyloxyethylamino)-7-nitro-2,l,3-benzoxadiazole (NBDAE), and photoswitchable acceptors, l -(2-methacryloxyethyl)-3, 3 -dimethyl-6-nitro-spiro(2//-l-benzo-pyran-2,2 -indoline) (SPMA). The UV radiation induces the change from colorless spiropyran derivatives in the outer part of the coating (7) to the fluorescent merocyanine form (2). Thus, FRET with the benzoxadiazole moieties in the inner part of the coating is enabled and the fluorescence color changes from green to red. By variation of the temperature and induction of a collapse of the PNIPAM chains (3), the FRET efficiency can be tuned (4). Reprinted, with permission, from [70], Copyright (2009) American Chemical Society...

Unlike the still-unknown 277-pyran which exists exclusively in the ring-opened form, 277-thiopyran is a well-characterized molecule. Nevertheless, the S-C(2) bond can be cleaved and this is the basis of the photochromic properties observed with spirobenzothiopyrans. Irradiation at 365 nm of the spiro[2/7-l-benzothiopyran-2,2 -indoline] 273 in both the solid state and in solution results in opening of the thiopyran ring and the formation of a colored metastable zwitterionic merocyanine (Equation 21). The open form exhibits solvatochromism, with Amax 588 nm in methanol and 673 nm in acetone. In solution, the thiopyran unit reforms rapidly when irradiation ceases, but continuous irradiation leads to the growth of crystals of the open form <2002JOC533>. 

Reaction of aryl Grignard compounds, obtained in situ by iodine-magnesium exchange, with C0CI2, presumably generates aryl radicals. In the presence of a double bond or aromatic ring an intramolecular radical cyclization may take place. This reaction was used for the synthesis of spiro-indolines.244 Oshima has applied cobalt-mediated tandem radical cyclization-cross-coupling reaction for the synthesis of benzyl-substituted heterocycles (Scheme 80).245... 

The first method is perhaps the most common, and is exemplified by the condensation shown in Scheme 3 of a 2-alkyl heterocyclic quaternary salt or the corresponding methylene base with a 2-hydroxy unsaturated aldehyde grouping (which usually is part of an aromatic ring, as in salicylaldehyde). These intermediates have given a broad assortment of spiropyran classes. The ready availability of 1.2.3.3.-tetraalkyl-3/f-indoleninium salts and salicylaldehydes has led to a large number of spiro-(2i/-l-benzopyran-2,2 -indolines) [this name will be used in preference to the correct T,3 -dihydrospiro(2//-l-bcnzopyran-2,2 -(2 //(-indole)]. A common acronym for this class, BIPS, will be used in this chapter as both singular and plural. 

A similar SERS study was carried out on indolinospironaphthopyran, its aza analog spironaphthoxazine, and the model compounds, 1,2,3,3-tetramethylindoline and 3,3-dimethylnaphthopyran. The orientation of the adsorbed spiro compounds and their indoline and chromene portions on the silver surface was determined. A goal of the work was to develop methods for using the high sensitivity and selectivity of SERS to study the photochromies and their fatigue products in polymer matrices.168... 

M. A. Gal bershtam, N. M. Przhiyalgovskaya, O. R. Khrolova, I. B. Lazarenko, G. K. Bobyleva, and N. N. Suvorov, Photochromic properties of some N-substituted 3,3-dimethyl-6 -nitro-indoline-2-Spiro-2 -2/7-chromenes, Chem. Heterocycl. Cpds., 1977, 1309-1313. 

S.-R Heum, M.-S. Hur, P. M. Kazmaier, and E. Buncel, Thermo- and photochromic dyes Indolino-benzospiropyrans. Part 1. UV-VIS spectroscopic studies of 1, .3,.3-spiro(2 //-1 -benzopyran-2,2 -indolines) and the open-chain merocyanine forms solvatochromism and medium effects on spiro ring formation, Can. J. Chem., 69, 1940-1947 (1991). 

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