Pyrrole diacetyl

Pyrrole and alkylpyrroles can be acylated by heating with acid anhydrides at temperatures above 100 °C. Pyrrole itself gives a mixture of 2-acetyl- and 2,5-diacetyl-pyrrole on heating with acetic anhydride at 150-200 °C. iV-Acylpyrroles are obtained by reaction of the alkali-metal salts of pyrrole with an acyl halide. AC-Acetylimidazole efficiently acetylates pyrrole on nitrogen (65CI(L)1426). Pyrrole-2-carbaldehyde is acetylated on nitrogen in 80% yield by reaction with acetic anhydride in methylene chloride and in the presence of triethylamine and 4-dimethylaminopyridine (80CB2036). 

Pyrrole, 2-cyano-l-(2-hydroxyethyl)-5-nitro-ipso substitution, 4, 243 Pyrrole, 2-cyano-l-methyl-photochemical rearrangement, 4, 42 photolysis, 4, 203 Pyrrole, 2-cyano-3-methyl-photochemical rearrangement, 4, 202 Pyrrole, 2-cyano-4-methyl-photochemical rearrangement, 4, 202 Pyrrole, 2-cyano-5-methyl-photochemical rearrangement, 4, 202 Pyrrole, diacetoxymethyl-synthesis, 4, 274 Pyrrole, 2,4-diacetyl-synthesis, 4, 218 Pyrrole, 2,5-diacetyl-synthesis, 4, 218, 219 Pyrrole, 2,4-dialkyl-... 

Figure 5. Profiles of volatiles for low-quality peanuts with contaminants, raw and roasted (I) ethanol (2) pentane (3) 2-propanol (4) acetone (5) methylene chloride (6) methyl acetate (7) 2-methylpropanal (8) chloroform (9) diacetyl (10) benzene (11) 3-methylbutanal (12) 2-methylbutanal (13) 2,3-pentanedione (14) fl-methyl-pyrrole (15) pyridine (16) toluene (17) hexanal (18) 2-methylpyrazine (19) 2-methylpyrrole (20) 2-heptanone (21) styrene (22) 2,5-dimethylpyrazine (23) 2-ethyl-5-methylpyrazine (24) 2-ethyl-3,6-dimethylpyrazine (25) phenylacetalde-hyde.

Although it is more usual to obtain the halogenoacyl derivatives of pyrrole and indole by direct acylation (see Section 3.05.1.2.6), it is possible to carry out electrophilic halogena-tion of acylindoles <79HC(25-3)357). 3,4-Diacetyl-l,2,5-trimethylpyrrole has also been reported to react with phenyltrimethylammonium tribromide to give the 3,4-bis(bromoacetyl) derivative, which cyclizes in the presence of a zinc-copper catalyst to yield 4,5,6,7-tetrahydro-l,2,3-trimethyl-4,7-dioxoisoindole (74CC1034). 

Acylation of the highly reactive indolizines may be achieved at the 3-position and, less easily, at the 1-position using acid chlorides, anhydrides and even esters (48CRV(42)6ll). 3-Acetylation of indolizine, 1,3-diacetylation of indole and 2,5-diacetylation of pyrrole have been effected with acetic anhydride at 140-200 °C (see Section 3.02.2.4.8 for details). The indolizines (49) and (50) are formed with ethyl chloroformate and ethyl benzoylacetate respectively. 

Fig. 6 Methyl 2-me.thyl-4//-thicno 3,2-hlpyrrole-5-carboxylate 48, methyl 3-acetyl-2-methyl-4//-thieno 3,2-b pyrrole-5-carboxylate 49a, methyl 2-methyl-3-propanoyl-4//-thieno [3,2-h]pyrrole-5-carboxylate 49b, methyl 3-chloroacetyl-2-methyl-4//-thieno[3,2-h]pyrrole-5-carboxylate 49c, methyl 3-dichloroacetyl-2-methyl-4//-thieno[3,2-h]pyrrole-5-carboxylate 49d, methyl 2-methyl-3-trichlomacctyl-4//-thicno 3,2-h]pyrrole-5-carboxylate 49e, methyl 2-methyl-3-(2-methylpropanoyl)-4/7-thieno[3,2- ]pyrrole-5-carboxylate 49f, methyl 3,6-diacetyl-2-methyl-4//-thieno[3,2-h]pyrrole-5-carboxylate 50a, methyl 6-acetyl-2-methyl-3-propanoyl-4//-thieno [3,2-h]pyrrole-5-carboxylate 50b, methyl 6-acetyl-3-chloroacetyl-2-methyl-4//-thieno [3,2-h]pyrrole-5-carboxylate 50c, methyl 6-acetyl-3-dichloroacetyl-2-methyl-4//-thieno[3,2-h]pyrrole-5-carboxylate50d, methyl 6-acetyl-2-methyl-3-trichloroacetyl-4//-thieno[3,2-h]pyrrole-5-carboxylate 50e, methyl 6-acctyl-2-mcthyl-4//-thicno 3,2-h pyrrole-5-carboxylate 51 [17]...

Many macrocyclic SBs have been prepared by condensation of different dicarbonyl precursors (head units (55), see Scheme 16) such as 2,6-diformylpyridine (56, R = H, 56a), 2,6-diacetylpyridine (56, R = CH3, 56b), 2,6-diformyl-4-Z-phenol (57, Z = C1- 57a, CH3-, 57b), 2,6-diacetyl-4-Z-phenol (57, Z = C1—, 57c, Z = CH3, 57d) thiophene-2,5-dicarbaldehyde (58), furan-2,5-dicarbalde-hyde (59), pyrrole-2,5-dicarbaldehyde (60), 2,6-diformyl-4Z-thiophenol (61, Z = CH3, 61a Z Bu1, 61b) or /3-triketones (62) with a wide range of different diamines (lateral chains). The majority of SB macrocycles are symmetrical and contain either phenol or pyridine as head units. Asymmetrical SB macrocycles have also been prepared. The SB macrocycles are designated [1 + 1] and [2 + 2] depending on the number of head and lateral units present (see Scheme 17). With certain precursors (i.e., 2,6-diacetylpyridine and l,3-diamino-2-hydroxypropane) [3 + 3] and [4 + 4] macrocyclic complexes have also been synthesized.177-179 The [2 + 3] condensation products have also... 

Arylene-bis-(pyrrole dicarboxylic acid anhydrides) were prepared by the condensation of two moles of diethyl diacetyl succinate with one mole of aromatic diamine, followed by hydrolysis and dehydration. Condensation of these novel dianhydrides with various aromatic diamines resulted in the formation of poly (amic acids) which were further condensed to polyimides. If the diethyl diacetyl succinate and aromatic diamine were reacted in equimolar quantities an N-(amino aryl) pyrrole diester was formed which can be further condensed to give polyimide directly. 

One modification of this procedure has. been to react the ethyl diacetyl succinate with diamine on an equimolar basis to give an N(aminophenyl)pyrrole diester which can then undergo further condensation to give the polyimide directly. 

Synthesis of bis(pyrrole) monomers. The condensation of ethyl diacetyl succinate with amines to give dialkyl esters of N substituted pyrroles proceeds in near quantitative yields to the bis(dicarboethoxy dimethyl pyrrole). 

Synthesis of N-(amino aryl) pyrrole dicarboxylate monomer. This type of polyimide precursor was prepared by the method of Knorr, who first described these preparations almost 100 years ago. The preparation proceeds readily by refluxing of ethyl diacetyl succinate with... 

The N-(aminophenyl) pyrrole dlester was prepared by a similar procedure using equal molar quantities of ethyl diacetyl succinate and an aromatic diamine. 

The A -nitrososulfonamide 70 was shown to be a convenient reagent for radical trifluoromethylation. UV irradiation of lb with 70 in the presence of diacetyl as a sensitizer led to 38b in 51 % yield (Table 1, entry 8). Distinct advantage of this method is easy handling of the solid 70 instead of gaseous CF3I or of the quite unstable bis(perfluoro-aIkanoyl)peroxides. 70 is assessable from trifluoronitroso-methane 69 in a one-pot procedure [35]. Te(CF3)2 was also used as a trifluoromethyl radical source for trifluoromethylation. The reaction proceeded under UV irradiation and led to a 25 1 mixture of pyrroles lb and 2b (Table 1, entry 9) [36]. 

Acetylation of amino-compoimd (XI) was earned out with acetic anhydride. By boiling of mixture of this compoimd with glacial acetic acid and acetic anhydride was obtained monoacetyl-derivative (XVII). The same compound was obtained when heated amine (XII) with acetic acid for a short time at 80-90°C. Boiling for 30-40 min mixture which consists of 7 and 8 compounds with ratio approximately 1 1, but by the increase of the boiling time up to 2-3 h practically only diacetyl-derivative (XVIII) was obtained. It should be noted, that there wasn t observed acetylation of pyrrole NH-group during the reaction. 

When two carbonyl groups are attached to opposite pyrrole rings (i.e., rings I and III or II and IV), the rhodo type effect is enhanced (e.g., 2-acetyl, 6-carbomethoxy, 1,3,5,8-methyl, 7-propionic acid). However, when the two carbonyl groups are on adjacent rings (e.g., 2,4-diacetyl-deuteroetioporphin III), or, when one carbonyl is in the 6-position and... 

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