Indoles, simple

The 2- and 3-methylsulfinylindoles, named itomanindoles A and B (60 and 61), were isolated from the Okinawan red alga Laurencia brongniartii, and both compounds exhibited optical activity (75). The structure of 60, and hence 61 by comparison, was determined by X-ray crystallography 

Indigo (497) has been isolated from mutant strains of Schizophyllum commune (484, 643) and Agaricus campester ( = A. campestris) (227) and from cultures of Auriculariopsis ampla (23) and identified by UV and infrared comparison with synthetic material. In Schizophyllum commune and Agaricus campester the blue pigment is accompanied by the red indirubin (498) (218, 227), and a yellow compound tentatively identified as isatin (499) (218). 

It is of intenjst to note in passing the occurrence in various Chaeto-mium species (133, 394), and elsewhere among the lower fungi (724), of analogues of the terphenylquinone (Section 2.1.2) and pulvinic acid pigments (Section 2.1.3) which derive not from phenylalanine or from tyrosine but from tryptophan. 

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Several derivatives of indolo[3,2-fi]carbazole, such as the system 185, have been claimed to arise from the reaction of suitably substituted simple indoles on treatment with thallium triacetate in acetic acid. A compound having the purported structure of 185 was thus isolated when 2,3-dimethylindole was used as the substrate [78UC(B)422]. Many years later, it was demonstrated that this product is in fact a derivative of indolo[2,3-c]carbazole (cf. Section VI) (99T12595). 

A nickel(II) species is also though to be an intermediate in the carbonyla-tion reaction of iodobenzene with (V-methylbenzaldimine and nickel carbonyl. Two addition modes of an ensuing aroylnickel(II) complex to the C=N double bond can be envisaged as routes to l-methyl-2-phenylindol-3-one and an ethylenediamine derivative (Scheme 47).7 5 The scope of this simple indole synthesis has not been assessed. 

Several investigators have developed the reductive cyclization of o-nitrostyrenes into an efficient synthesis of indoles. Thus, research by the groups of Watanabe [458, 459], Sbderberg [460, 461], and Cenini [462, 463] have established this reductive Pd-catalyzed AMieteroannulation reaction as a viable route to simple indoles and fused indoles (372) as shown below. Ohta... 

The final phase of our syntheses of vinblastine and analogous compounds required closure of the piperidine ring in the seco cleavamine part of the indole-indoline compounds 162 and 163. We had originally studied this reaction with the simple indolic C-16 and C-20 unsubstituted C-16 epimeric carbomethoxy seco cleavamines 164 and 165 and found that on cyclization they produced, through conformations 166 and 167, almost exclusively quaternary salts 168 and 169, which on debenzylation gave... 

L-tryptophan Indole alkaloids Indole Simple indole Arundacine... 

This structural group of indole alkaloids covers simple indole alkaloids (e.g., tryptamine, serotonin, psilocin and psilocybin), /3-carboline alkaloids (e.g., harmine), terpenoid indole (e.g., ajmalicine, catharanthine and tabersonine), quinoline alkaloids (e.g., quinine, quinidine and cinchonidine), pyrroloindole... 

The a for structural development of serotonin (simple indole alkaloid) is L-tryptophan, and the j3 is 5-hydroxy-L-tryptophan (Figure 64). Serotonin is a monoamine. It is a hioactive alkaloid known as a neurotransmitter. It has been found in the cardiovascular system, in Wood cells and the peripheral and CNS. 

Figure 64. Structural development of simple indole alkaloids.

Hibino, S. and Choshi, T. 2001. Simple indole alkaloids and those with a nonrear-ranged monoterpenoid unit. Nature Product Reports, 18 66-87. 

Simple indole alkaloids 8, 111, 112, 113 Simple phenylamine alkaloids 110 Simple tetrahydroisoquinoline alkaloids 7,... 

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. 

E. Naturally Occurring 1-Hydroxyindole Derivatives 1. Simple Indoles... 

In the case of vinyl compound 205 in the reaction with TCNE, the ultraviolet spectrum of the adduct was that of a simple indole rather than that of the oaminostyryl chromophore of the [4 + 2]-adduct, suggesting that the adduct is the cyclobutane 206 from a [2 + 2]-cycloaddition (81AJC1483). 

A. Simple indoles, carbazoles, carbolines, and physostygmine type alkaloids 106... 

Somei, M., and Yamada,F. (2003). Simple indole alkaloids and those with nonarranged monoterpenoid unit. Nat. Prod. Rep. 20,171-211. 

The simple indole alkaloids harman (27) and harmine (28) are also susceptible to biotransformation. Polystictus versicolor metabolizes both 27 and 28 to unidentified products, formed in a yield of 50% in the case of 28 (42). Mammalian liver preparations perform an oxidative O-demethylation of harmine (28) to produce harmol (29) (45). The supernatant fraction from the lO.OOOg centrifugation of liver homogenates of cow, mouse, rabbit, guinea pig, rat, and cat were all effective in O-demethylation, the highest yields (90%) being obtained after incubation for 30 min with the preparations from cow and mouse liver (45). No other products were detected from the biotransformation of harmine by the liver preparations mentioned above,... 

Keech, P. G. and Bunce, N. J. (2003) Electrochemical oxidation of simple indoles at a Pb02 anode. J. Appl. Electrochem. 33, 79-83. 

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