Indoles carbonate

Kostic el al. discovered that Pd11 complexes, when attached to tryptophan residues, can rapidly cleave peptides in acetone solutions to which a stoichiometric amount of water is added, for hydrolysis.436 The indole tautomer in which a hydrogen has moved from the nitrogen to C(3) is named indolenine. Its palladium(II) complexes that are coordinated via the nitrogen atom have been characterized by X-ray crystallography and spectroscopic methods.451 Binuclear dimeric complexes between palladium(II) and indole-3-acetate involve cyclopalladation.452 Bidentate coordination to palladium(II) through the N(l) and the C(2) atoms occurs in binuclear complexes.453 Reactions of palladium(II) complexes with indole-3-acetamide and its derivatives produced new complexes of unusual structure. Various NMR, UV, IR, and mass spectral analyses have revealed bidentate coordination via the indole carbon C(3) and the amide oxygen.437... 

In the intervening years, indoleboronic acids substituted at all indole carbon positions have found use in synthesis. For example, Claridge and co-workers employed 94 in a synthesis of isoquinoline 95 under standard Suzuki conditions in high yield [114], Compound 95 was subsequently converted to the new Pd-ligand l-methyl-2-diphenylphosphino-3-(l -iso-quinolyl)indole. 

Indole-carbonic acid, 5,7-Dinitro (called 5,7 Trinitroindol carbonsaiire or Dinitrostrychol in Ger). 

A novel procedure for the oxidative cleavage of indole carbon double bonds in the presence of H2O2 using plant cell cultures, as a catalytic system, led to benzazonine diones 297 (Scheme 54) <2004TL8061>. 177-Benzo[ ][l,4]diazonines 298 were obtained in a highly substituted form and in high yields by ozonolysis of 1,2,3,4-tctrahydro-9//-pyrido[3,4- indole derivatives 296 (X = NAc) <2000JME3518>. 

Since its discovery the Pictet-Spengler cyclization has formed the basis of numerous syntheses of alkaloids containing aromatic subunits. This high-yielding reaction involves, in its broadest sense, nucleophilic attack on an iminium ion by the Tr-electrons of a tethered aromatic moiety. In the classical reaction a substituted P-phenethylamine is condensed with an aldehyde under acidic conditions to produce a te-trahydroisoquinoline (Scheme 16). A useful variant of the Pictet-Spengler reaction, which provides tetr ydro-(3-carbolines and their derivatives, involves the condensation of a tryptamine derivative and an aldehyde (Scheme 16). Whether nucleophilic attack on the resulting iminium ion occurs initially at the a- or -indole carbon is a topic of current debate and, indeed, there is evidence to suggest that the mechanistic pathway could be substrate dependent. ... 

Interestingly, when the same indole-3-carboxaldehyde derivative 65 is subjected to Diels-Alder reactions with Danishefsky s diene (52), either under thermal or hyperbaric activation, it is the aldehyde and not the indole carbon-carbon double bond that serves as the dienophilic component (Scheme 19) [34]. The hetero-Diels-Alder reaction with the carboxaldehyde proceeded at quantitative conversion (82% yield) under thermal conditions (12 equiv Danishefsky s diene, 170°C, 24 h) and provided the cycloadduct 69 in quantitative yield under hyperbaric conditions (12 equiv Danishefsky s diene, 45°C, 96 h, 12 kbar). 

A similar mechanism was also postulated by Barrow et al. for the incorporation of the reversed isoprene unit at the indolic 3-position of roquefortine (see Schemes 22 and 25) [44] to date there is no experimental support published in the literature for the notion that the reverse prenyl unit at ei er the 2-position, as is found in echinulin, or the 3-position, as is found in roquefortine, is introduced indirectly at the indole nitrogen (or some other position) followed by migration. All evidence, both direct and indirect, points to the direct S attack of the pertinent indole carbons on dimethylallylpyrophosphate. 

Dicarboxy-vlnyl]-indol-carbons 8aure-(2) tidfttbylea er 28 II141. 

Methyl-indol-carbons ure-(2)-[methyl-(. . dimethoxy thyl) amid] 83 II 51. 

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