Polyheterocyclic compounds

The nitration of the polyheterocyclic compound 226 leads to the formation of moisture-sensitive nitration products, which undergo further oxidation to give o-quinone-like species (Scheme 55) <1996JOG1898>. 

Several polyheterocyclic compounds containing a condensed 1,2,4-triazole nucleus, such as 3,5-disubstituted thiazolo [2,3-r][ 1,2,4] triazoles, are thermostabilizers for polypropylene and polycaproamide <2003MI2>. Triazolo[3,4-A][l,3]benzothiazoledicarbonitrile derivatives are used to prepare hexazocyclanes-fluorophores as active media for liquid and solid lasers, scintillators, and for transformation of short-wave radiation to long-wave radiation <2004RUP2238276>. 

Polyheterocyclic compounds with oxygen and nitrogen heteroatoms include complex alkaloids such as morphine. 

This occurs for 2-hydroxyphenylacetones, hydroxylated deoxy-benzoins, and, as in the simplest case (R=H), o-hydroxyarylacetal-dehydes. The reaction is especially suitable for the synthesis of polyheterocyclic compounds with fused benzofuran rings. 

Complex benzofurans, such as N-substituted 3-oxo-l,3-dihy-drobenzofuro[2,3-c]pyrroles (95),263 or bacteriostatic substituted 5,6,7,8-tetrahydrobenzofuro[2,3-6]pyridines,270 4a-alkoxy-l,2,3,4,4a, 9b-hexahydrobenzofuro[3,2-c]pyridines and polysubstituted benzo-furo[3,2-c]pyridines,271 and other polyheterocyclic compounds with sulfur or nitrogen atoms272,273 have also been synthesized by this method. 

The condensation of o-aminobenzenethiol with pyridine-2,6-dicarbaldehyde does not form the corresponding Schiff base but a polyheterocyclic compound which behaves as a tridentate ligand towards nickel(II).2365 In contrast the reaction of 2-(2-pyridyl)benzothiazoline with nickel(II) results in the opening of the heterocyclic ring and in the formation of a Schiff base ligand which coordinates to nickel(II) as a mononegative tridentate ligand.2366,2367... 

Several one-pot syntheses are closely related to MCRs that have irreversible final steps, although they are unions of two usually reversible M-3CRs, since their products are rather stable polyheterocyclic compounds. The first such procedure was introduced by Robinson in 1917 [48a], who synthesized the tropinone 59 from succindialdehyde 56, methylamine 2b and the methyl ester of acetonedicarbocylic acid 57 (Scheme 4.28). Two decades later, Schopf et al. accomplished some progress with a closely related synthesis [48b],... 

Starting from 1,2-diaminobenzene (X) the following sequence of reactions was performed to synthesize the polyheterocyclic compound D ... 

Several synthetic polyheterocyclic compounds are angiotensin II antagonists. Bromobenzofuran... 

Nickl J, Naarmann H, Moehwald H (1985) Use of polyheterocyclic compounds of a certain structure as electrode material. Gct Patent DE 3409655 A1... 

Although many of the anilines used in the Sandmeyer isatin synthesis have minimal functionality, examples exist where potentially sensitive motifs can survive the harsh reaction conditions. The 6-azauracil substituted aniline 39 could be converted to isatin 40 en route to the polyheterocyclic compound 41. A trifluoroacetyl protected amine could also be carried through the two-step Sandmeyer sequence to yield the isatin of interest. ... 

Fused polyheterocycles are also often present in active natural products like those depicted in Figure 6.7. In the previous section, few examples of efficient synthesis of this kind of molecules, containing indole in their structure, have been shown. Some further instances of spiroin-doline preparation will be compiled in the section of dedicated to spiro-type polyheterocyclic compounds (Section 6.4.3). 

MCRs are powerful means for the construction of multiple bonds in functionalized molecules. They introduce molecular diversity in only one step and do so in a highly efficient and convergent manner. More than one and a half century after their discovery, MCRs have proven to be a very efficient manner to reach complex organic molecules with relevant biological activities, from polyheterocyclic compounds to peptide derivatives. 

So, M., Liu, Y, Ho, C., et al. (2011). Silica-Supported Gold Nanoparticles Catalyzed One-Pot, Tandem Aerobic Oxidative Cyclization Reaction for Nitrogen-Containing Polyheterocyclic Compounds, Chemcatchem, 3, pp. 386-393. 

The in situ prepared catalyst Ru(OAc)2(p-cymene) in the presence of the K2CO3 was almost as active as the isolated complex and was preferentially used [65]. This catalytic system was selected for the efficient preparation of a variety of polyheterocyclic compounds or tridentate ligands such as the tripodal tris-1,2,3-(heteroaryl)benzene [(Eq. 8)] [65]. The same type of diarylated derivatives and polyheterocyclic compounds can now be preferentially prepared in diethyl carbonate, a non-toxic solvent, instead of NMP even if the reaction is slower [71]. 

All proposed reaction pathways end with reductive elimination of palladium(O) and formation of simple, condensed, or polyheterocyclic compounds. 

Functionalized heterocyclic zinc reagents are quite usefiil for the preparation of polyfunctional heterocycles. The pyridylzinc derivative 400 has been prepared by reductive lithiation followed by a transmetalation with zinc bromide (Scheme 2-130, eq. (a)). Its cross-coupling with a quinolyl chloride provides the new polyheterocyclic compound 401 in 81% yield. The selective functionalization of positions 3 and 4 of... 

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