Simple indole derivatives

The simple base gramine 6.227) is known to derive from tryptophan 6.225), in three plants from different families. C-2 is lost but apparently not the side-chain nitrogen [165]. 

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Whereas simple indole derivatives are rare in marine Streptomycetes, they are rather common amongst the North Sea bacteria so far investigated. The extracts of strain Hel 45 that contain the diketopiperazines cyclo(Phe, Pro) and cyclo(Tyr, Pro), however, are dominated by large amounts of unsubstituted indole, the known dimer 3-(3,3 -diindolyl)propane-l,2-diol [109] (21) and various other, still unidentified, indole derivatives. 

The indole group of compounds is conveniently divided into the so-called simple indole derivatives and the indole alkaloids, which often have complicated stmctures, and indole dyes. Thus it was demonstrated that not all compounds are completely separated by either the basic eluent, methyl acetate-isopropanol-25% ammonia (45 35 20, v/v), or the acidic eluent, chloroform-96% acetic acid (95 5, v/v). Therefore one combines the effects of both of these eluent systems in the 2-D TLC method in this way, 14 simple indole derivatives and anthranilic acid can be separated. Compounds are separated into groups according to their polarities. ... 

The second component of the macralstonine molecule, which contains the tautomeric hydroxyketone grouping, possesses a simple indole chromophore this was readily deduced from the UV spectrum of macralstonine which, after substraction of the spectrum of alstophylline, gave a curve identical with that expected for a simple indole derivative. Evidently the chromophores present in macralstonine are not conjugated. 

Cimino, G. and S. E>e Stelano 1978. Chemistry of Mediterranean Gorgonians Simple indole derivatives from Param-uricea chamaeleon Comptes Pertdus Bio-chemie Physiologie Serie C 61 361—362. 

Muthusamy and coworkers [67, 68] have examined the regioselectivity (with respect to dipole orientation) of intermolecular cycloadditions of carbonyl ylides with a variety of N-substituted indoles. l-Diazo-3,3-dimethylpentane-2,4-dione (126), upon treatment with rhodium (11) acetate and simple indole derivatives (125), might be expected to give a mixture of regioisomers 127 and 128 however, only hexahydro-2//-carbazol-2-ones 127 were observed in 86-97% (Scheme 31). 

The indole group of compounds is conveniently divided into the so-called simple indole derivatives and the indole alkaloids, which often have complicated stmctures, and indole dyes. Thus it was demonstrated that not all... 

H. Kaldewey Simple Indole Derivatives and Plant Growth Regulators 471... 

As a simple indole derivative, the aromatic amino acid tryptophan (2-amino-3-(3-indolyl)-propionic acid) plays an important part in animal and plant metabolism. Its degradation via kynurenine leads, e. g., to formation of nicotinic acid and its amide or of ommochromes which have been found as pigments especially in crustaceans and insects. Observations made on mutant strains of insects and of the mould Neurospora crassa, in which the biosynthetic routes mentioned are blocked, have given a profound insight into the physiology of gene activity [6]. 

The following solvent combinations, in order of use, have been so far proposed (Roman numerals refer to Tables 88/89, capital letters to Table 90) XIV -> XVI a [120] and V->IV [19] for separating simple indole derivatives, particularly from auxin metabolism (the second combination is suitable for the methyl esters of the acids also) XVII-> XIV [12], XV-> XVIa [9] isopropanol-25% ammonium hydroxide-water (80 + 4 + 8) IX [90] for separation of urine metabolites A B for hydroxyskatoles and C D for hydroxyindoles. 

The van Urk-reagent (No. 73) yields relatively well differentiated colours with simple indole derivatives and sensitivity is quite high (cf. [13, 97] concerning the chemistry of the reactions). 

The total synthesis of the complex natural product strychnine (Section 25-8), containing seven fused rings and six stereocenters, has been steadily improved over a half-century of development of synthetic methods. The first synthesis, reported in 1954 by R. B. Wo ward (Section 14-9), started from a simple indole derivative (Section 25-4) and required 28 synthetic steps to give the target in 0.00006% overall yield. A more recent synthesis (in 2011) took 12 steps and proceeded in 6% overall yield. 

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