3-aryl, tables

Carbonyls of aroyloxyl groups (R2 = Aryl, Table 2, entries 42-52 and 59-68) range from 1750 to 1767 cm-1 and are similarly increased relative to normal aromatic esters (1715-1730 cm-1). Most benzoyloxy compounds give carbonyls between 1760 and 1765 cm-1 but those that are para substituted with donor groups, as well as those with polycyclic aroyloxyl groups, have carbonyls in the lower range of 1750-1760 cm-1. 

Shibata and coworkers463 464 have used [Co(acac)3], K[Co(CN)2(acac)2] and K3[Co(CN)5I] to prepare a wide range of the more classical Com complexes cis- and fran.s-[Co(acac)2(PR3)2]+, [Co(CN)2(acac)(PR3)2], and tra s-[Co(CN)4(PR3)2] (R = alkyl, aryl Table 36). They report H, 5lP and visible-UV spectra and some simple reactions. /rans-[Co(acac)2(PMe2Ph)2]+ aquates to blue-green rru7W-[Co(acac)2(PMe2Ph)(H20)]+ in aqueous ethanol, and in the presence of charcoal it isomerizes to an equilibrium mixture containing mostly the cis isomer. 

Thus, the reaction of both aryl (Table 9, entries 1-3) and alkyl diazo ketones (entries 5 7,... 

Thus, the reaction of both aryl (Table 9, entries 1-3) and alkyl diazo ketones (entries 5-7, 9-11) with (HF) /pyridine and a halide source gives a-fluoro-a-halo ketones. The best yields are generally obtained in the case of the fluoroiodo derivatives (entries 3, 7 and 11). Diazo... 

Before the 1970s, Ziegler-Natta catalysts for a-olefin production were normally prepared from certain compounds of transition metals of Groups IV-VI of the periodic table (Ti, V, Cr, etc.) in combination with an organoraetallic alkyl or aryl (Table I). Practically all subhalides of transition metals have been claimed as catalysts in stereoregular polymerization. Only those elements with a first work function <4 eV and a first ionization potential <7 V yield sufficiently active halides, that is, titanium, vanadium, chromium, and zirconium (7, Only titanium chlorides have gained widespread acceptance in crystalline polyolefin production. 

As all free-radical arylation reactions, the ptGBH reaction produces a mixture of all three isomers if the arene is unsymmetrical [61,76,79]. The isomer distribution can be seen from the following examples of monosubstituted benzene arylation. Table 3. A number of instances have shown that isomer distribution is indifferent to the catalyst used, this strongly suggests that an aryl radical as an actual arylating agent is formed under either phase transfer or classical GBH conditions. 

Up until now, only aryl bromides have been applied successfully in this a-arylation reaction. It was Kawatsura and Hartwig [26], who, in 1999, reported the first application of aryl chlorides as electrophiles in the a-arylation of ketones. The authors established that the catalyst containing DTBPF (l,l-bis(di-ferf-butylphosphino)ferrocene) and Pd(dba)2 (dba=fr is, fraws-dibenzylideneacetone) provided clean chemistry with chloroarenes at only 70 °C (Table 8.1). Electron-neutral and even electron-rich chloroarenes gave the coupled products in high yields and even sterically hindered aryl chlorides were suitable substrates to be arylated (Table 8.1). Basically, the overall reactivity of chloroarenes was similar to that of bromoarenes. It was also observed that the diphosphane ligand DTBPF was coordinated in a manner to the arylpalladium enolate intermediate [26]. Sterically hindered monophosphanes (e.g., P(tBu)3, Table 8.1) afforded excellent results for the arylation of ketones with aryl chlorides (Table 8.1). However, much more work is required in order to make this method more applicable on a larger scale, especially when using aryl chlorides. 

Band 4, 5-9411 (1683 cm. ). Aryl carboxylic acid C=0 stretching vibration (Table IV). 

Retrosynthetic path b in Scheme 3.1 corresponds to reversal of the electrophilic and nucleophilic components with respect to the Madelung synthesis and identifies o-acyl-iV-alkylanilines as potential indole precursors. The known examples require an aryl or EW group on the iV-alkyl substituent and these substituents are presumably required to facilitate deprotonation in the condensation. The preparation of these starting materials usually involves iV-alkyla-tion of an o-acylaniline. Table 3.3 gives some examples of this synthesis. 

The simplest procedures for 2-acylation involve reaction of an jV-protected 2-lithioindole with an acyl halide, anhydride or ester. Such reactions typically give good yields of 2-acylindoles. Table 10.3 presents some examples. Aryl... 

The best procedures for 3-vinylation or 3-arylation of the indole ring involve palladium intermediates. Vinylations can be done by Heck reactions starting with 3-halo or 3-sulfonyloxyindoles. Under the standard conditions the active catalyst is a Pd(0) species which reacts with the indole by oxidative addition. A major con.sideration is the stability of the 3-halo or 3-sulfonyloxyindoles and usually an EW substituent is required on nitrogen. The range of alkenes which have been used successfully is quite broad and includes examples with both ER and EW substituents. Examples are given in Table 11.3. An alkene which has received special attention is methyl a-acetamidoacrylate which is useful for introduction of the tryptophan side-chain. This reaction will be discussed further in Chapter 13. 

The Suzuki coupling of arylboronic acids and aryl halides has proven to be a useful method for preparing C-aryl indoles. The indole can be used either as the halide component or as the boronic acid. 6-Bromo and 7-bromoindolc were coupled with arylboronic acids using Pd(PPh3)4[5]. No protection of the indole NH was necessary. 4-Thallated indoles couple with aryl and vinyl boronic acides in the presence of Pd(OAc)j[6]. Stille coupling between an aryl stannane and a haloindole is another option (Entry 5, Table 14.3). 

The condensation of a-haloketones with monosubstituted alkyl or aryl-selenoureas (25) leads to 2-alkylamino- (26. 27) or 2-arylaminOselana-zoles (28) while disubstituted selenoureas give 2-(dialkylamino) selenazoles (26. 27) (Table X-3a). 

TABLE II 13. 4 ALKYL, 4-ARYL. OR 4-HETEROARYL 2-AMINO miAZOLES... 

Some 5-substituted 2-aminothiazoles with alkyl (15, 173, 175, 224, 366, 396), ester (173, 184, 220), aryl (115, 265, 396, 414), a-naphthyl (463), sulfur and sulfones derivatives (329, 373), isonitrosomethyl (772), and chloro groups were synthetized from the corresponding a-haloaldehyde and thiourea in lower yield (Table 11-14). 

This method has been applied to the synthesis of 4-methyl (659), 4-aryl (416, 519, 659), 4,5-dimethyl (137, 220, 221), 4,5-dialkyl (229, 681), 4-methyl-5-O-acetoxyethyl) (229), 4-methyl-5-(j3-carbethoxyethyl) (229), 4-ary 1-5-bromo (579), and 2-chlorothiazoles from the corresponding a-thiocyanatoketones (Table 11-28). 

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