Heteroaryl groups

Thiazoles with Heterocyouc Substituents. Thiazoles with heterocyclic substituents in the 2- or 4-position have been synthesized (Table II-9). Thus thioacetamide (or its a-substituted derivatives) react with bromomethyl heteroarylketones under reflux in alcohol to give the corresponding 2-methyl-4-heteroarylthiazoles heteroaryl groups in the 4-position were 2 -thienyl (213, 692) a-pyrrolyl and 3-method derivatives... 

This method is suitable only for the preparation of 4-substituted and/or 3,4-disubstituted derivatives, the substituents being only alkyl, aryl or heteroaryl groups. The presence of electron-withdrawing groups in the unsaturated side chain prevents the cyclization step. This is understandable if the influence of such groups on the stability of the intermediate carbonium ion is considered. Of more limited application is the analogous cyclization of diazotized o-aminophenylpropiolic acids, the reaction being referred to as the Richter synthesis (Scheme 70). A related synthesis (also referred to as the Neber-Bossel synthesis)... 

Heteroaryl groups are present in the 4-pyridyl-ethynyl compounds81,99,100 and their extended variants with C=C-C6H4-C=C-pyr-4 ligands.81,99 These compounds can be quaternized with Mel or coordinated to a metal complex at their terminal pyridyl functions to give species addressed as molecular rods or molecular wires.81,99 Similar reactions were carried out with 3-phenanthrolinyl-ethynyl complexes,62 and special examples are also known with R based on calixarenes.51... 

R = Aryl or Heteroaryl groups X = H or alkyl/aryl grouping... 

Tosyloxy)methyl 2-hetarylketone was used as the reagent (heteroaryl groups furan and thiophene derivatives). 

According to the demand for insolubility in water and the commonly used organic solvents, substituents attached to the alkyl, aryl, or heteroaryl groups should not contain sulfo (S03H) groups or long-chain alkyl groups which render the colorant soluble. 

In 2004, Taylor and Jacobsen suggested a procedure for the enantioselective acetyl-Pictet-Spengler reaction, that is the cyclization of electron-rich aryl or heteroaryl groups onto N-acyliminium ion enabling access to substituted tetrahydro-P-carbolines and tetrahydroisoquinolines that are core structure elements in natural and synthetic organic compounds [202, 203]. Screening various thiourea catalyst candidates such as 47 in the formation of model product Np-acetyl-... 

Dichloro-5-methoxyphenyl)amino]thieno[3,2- ]pyridine-6-carbonitriles substituted with heteroaryl groups at position C-2, 160, have been found to inhibit Src kinase activity. The highest activity in Src and cell assays has been found with a 2,5-furan or 2,5-pyridine substituent at C-2 <2005BML4681, 2005JME3891>. 

A potential way to avoid the formation of undesired side products, like in 7.2., is the use of such boron compounds that have only one transferable group. In most cases boronic acids are the compounds of choice, as they are easy to prepare, insensitive to moisture and air, and usually form crystalline solids. In certain cases, however the transmetalation of the heteroaryl group might be hindered by the formation of stable hydrogen bonded complexes. In such cases the use of a boronate ester, such as in equation 7.4., provides better yields. For example pyridine-2-boronic acid dimethylester coupled readily with a bromoquinoline derivative under conditions similar to 7.3. (potassium hydroxide was used as base and tetrabutylammonium bromide as phase transfer catalyst).6... 

In the case of phosphonium salts substituted by an heteroaryl group, the furfuryl group is easily cleaved744 2,4-pyridindiyl bis(phosphonium) salts have been used as source of 2-pyridylphosphonio compounds745 (reaction 221). Clearly, the presence of... 

Pseudo-bases derived from 2-unsubstituted 1,3-dialkylperimidinium salts disproportionate into 1,3-dialkylperimidones and l,3-dialkyl-2,3-dihydroperimidines, the former always predominate. By contrast, l-aroyl-3-alkylperimidinium salts (203), formed in situ from l-/ -perimidines and aroyl chlorides, produce pseudobases (204) which exist exclusively in the acyclic form (205). Interestingly, heating with alkali cleanly converted (205) into the corresponding 1,2-disubstituted perimidines (206). This reaction is of preparative significance for the introduction of aryl and heteroaryl groups in position 2 of perimidines (81RCR1559). 

This is the intramolecular version of the previous reactions, and the precursors of the Z2E fragment are the same (e.g. disilanes)54. The reaction, however, has been applied only to 1,6-diynes bearing two aryl (or heteroaryl) groups in positions 1 and 7, in the presence of a Ni-catalyst. 

The position of the substituents is given according to IUPAC nomenclature using the prefixes 1-, 3-, and 5-. Formazans unsubstituted in the 1- and 5-positions and 1,5-dialkyl-substituted formazans are unknown. Aryl or heteroaryl groups are the most common 1,5-substituents. The 3- or meso position can be occupied by a variety of substituents (e.g., aryl, heteroaryl, H, OH, SR, halogen, N02, CN, and alkyl). 

I. Claim 1 is drawn to a heteroaryl group of class 548, subclass 490.37... 

Fig. 4. Structural features important for the binding of arylpiperazines at 5-HT1A receptors (62,64). The Aryl group is a phenyl, substituted phenyl, heteroaryl, or substituted heteroaryl group, whereas the Spacer is usually a branched or unbranched carbon chain of two to five atoms in length (and might contain a heteroatom in place of one of the methylene groups). The Terminus is typically an amide, reverse amide, imide, or aryl group the terminus function can be quite large, as this area is probably associated with a region of bulk tolerance.

The Pictet-Spengler reaction, the cyclization of an electron-rich aryl or heteroaryl group onto an imine electrophile, is the established method for the synthesis of tetrahydroisoquinoline and tetrahydro-/ -carboline ring systems. Catalytic asymmetric approaches to these synthetically important structures are mostly restricted to asymmetric hydrogenations of cyclic imines [77, 78]. In a noteworthy... 

Moreover, 4(or 5)-heteroarylmethyl-imidazoles 67 can be obtained by a photo-induced ring-contraction of 4-heteroaryl-substituted l,4(or 3,4)-dihydropyrimi-dines 65 easily prepared by reaction of the corresponding pyrimidine with hetero-aryllithium (Scheme 12.19). The irradiations were performed in acetone in a Rayonet preparative photoreactor equipped with RUL 300 lamps, and the products isolated in 43-57% yields. The reaction was determined by the anion-stabilizing effect of the heteroaryl group R1, which affects the thermal development of the bicyclic intermediate 66 [44]. 

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