Indoline, structure

The foregoing information suggested a 17-hydroxy-A-propionyl-indoline structure, and this was fully confirmed by the NMR-spectrum (Table IV) which showed the presence of three aromatic protons and a hydrogen-bonded phenolic hydroxyl group (singlet at 10.88 8). More important, the portion of the spectrum due to aliphatic protons was very similar to that of aspidolimine (LIII), except that no peaks were found that corresponded to a methoxyl group or a terminal methyl of an ethyl side chain. Other characteristic features of the aspidospermine (II)... 

A fused heterocyclic quinolone is similarly available by ring closure of an aminomethy-lene derivative with indoline structure (equation 217). 

Important synthetic thrusts in this area have been described. The mechanism of the transformation (4) -> (6) which proceeds in 35 % yield [80 % from (5)] has been shown to require both phenolic hydroxy-groups in (4) unblocked and therefore must involve pp-coupling and further oxidation to the intermediate (5). The high yield may be due to the adoption of a favourable conformation and anion-radical exchange in the precursor of (S). An alternative indoline structure was eliminated from consideration as an intermediate since it... 

The most remarkable characteristic of the alkaloids is the frequency of dioxipiperazine derivatives (particularly polysulphanyl derivatives) and the indolic-indolinic structure. 

Reduction of indolenines with sodium and ethanol gives indolines. The pentachloropyr-role, obtained by chlorination of pyrrole with sulfuryl chloride at room temperature in anhydrous ether, was shown by spectroscopic methods to have an a-pyrrolenine (2H-pyrrole) structure (222). It is necessary, however, to postulate that it is in equilibrium with small but finite amounts of the isomeric /3-pyrrolenine form (3//-pyrrole 223), since pentachloropyrrole functions as a 2-aza- rather than as a 1-aza-butadiene in forming a cycloadduct (224) with styrene (80JOC435). Pentachloropyrrole acts as a dienophile in its reaction with cyclopentadiene via its ene moiety (81JOC3036). 

Figure 2. Structures of phthalazine (32,33), pyrimidine (34,35), and indoline (36,37) ligands used in the Sharpless AD and composition of AD-mix a and AD-mix p.

Although phthalocyanines are structurally similar to porphyrins such as hemoglobin, chlorophyll a and vitamin B12, they do not occur in nature. Formally, phthalocyanines can be regarded as tetrabenzotetraazaporphyrins and as the condensation products of four iso-indoline units. 

Over the years, many spiropyran structures have been prepared. The pyran component consists of benzopyran or naphthopyran and the heterocyclic part consists of indoline, benzothiazoline, benzoxazoline, benzoselen-azoline, phenanthridine, acridine, quinoline, benzopyran, naphthopyran, xanthene, benzodithiole, benzoxathiole, and saturated heterocyclic rings such as pyrolidine and thiazolidine. 

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. 

Substituent effects on the are remarkable. Electron-withdrawing groups at the 5 -position, e.g., 5 -nitro-substitution (indoline component), and donor substituent at the 8-position (benzothiopyran component) in 44 leads to a longer wavelength shift. As the polarity of the solvent increases, the max of the colored form of spiroindolinobenzothiopyran results in hypsochromic shift. This can be interpreted as the existence of a polar structural component of the colored form in the ground state. Kinetic study has suggested that the zwitterionic structure largely contributes to the colored form of 6-nitrospiroindolinobenzothiopyran, as well as spiropy-rans.97 Based on H-NMR and X-ray analysis,98 99 the existence of an... 

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. 

The structure-function relationship of the indole-indoline binary alkaloids was relegated to obscurity until the recent achievement of methodologies for their complete syntheses (see Chapter 2, this volume). Our work with C-20 congeners of VBL has established that the complex interactions between this molecule and tubulin or microtubules can be modified by structural alteration. The various, concentration-dependent reactions of VBL with the microtubule system in vitro are sensitive to subtle modifications at a single molecular locus. In addition, these reactions are distinctive on a mechanistic level as seen from the unique activity profiles of most of our C-20 alkyl congeners. At first light, we can look toward the future with secured optimism. 

Fu and co-workers expanded the scope of amine KR to include indolines [100], However, as the initial conditions developed for aryl alkyl i ec-amines were unsuc-cessfnl dne to the low nucleophilicity of the catalyst, a few structural modifications were introdnced. Hence, after screening varions catalysts and achiral acyl donors, the use of a bulky pentacyclopentadienyl-derived catalyst in conjunction with an... 

As part of a study of the reactions of arenesulfonyl azides with indoles, Bailey et al.lu obtained a compound from the action of tosyl azide on indoline-2-thione to which they ascribed structure 114 (R = H). In contrast, N-methylindoline-2-thione gave only a low yield of 114 (R = Me) under the same conditions. Diazo-transfer via an intermediate 115 is thought to be involved when R = H, facile loss of toluene-p-sulfonamide leads to 114a, but when R = Me, loss of the same fragment leads mainly to other products. 

The C-2 and C-3 hydroxy derivatives of pyrrole are special in the sense that the tautomeric equilibria favor the pyrrolinone structures (see Section 3.04.6.2). Furthermore, the general synthetic methods are not usually applicable so that we will call attention in this section not only to the methods of directly introducing these substituents, which are rare, but also to those ring construction processes which specifically give the pyrrolinones and indolinones. The indole derivatives have widely used trivial names, oxindole (5) for indolin-2-one and indoxyl (6) for indolin-3-one, Carbocyclic hydroxy substituents in indole and carbazole, on the other hand, for the most part act as normal aromatic phenolic groups. These compounds are usually prepared by application of the standard ring syntheses. 

The extension of the use of lactams to include indolin-2-ones provides a Vilsmeier-type methodology for the construction of biindolyl systems, which are of considerable current interest.37,39-43 In this situation, the initially formed imines are indolenines, which readily isomerize to the related 2-indolyl derivatives.43 In view of our general interest in activated indoles, as well as a specific interest in continuing to synthesize structures containing indoles directly linked to each other, we investigated not only reactions with indolinone itself but also with substituted derivatives. These were variously methoxy-substituted at C-4 and C-6, and in some cases substituted also at C-3 with methyl, phenyl, or dithiolan groups. 

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