4- Methyl-3- pyrrole-2-carboxylates

Methyl pyrrole-l-carboxylate (14) and hot dimethyl acetylenedi-carboxylate give trimethyl pyrrole-1,3,4-tricarboxyIate (15) and acetylene, presumably through the addition-elimination sequence shown. Dimethyl acetylenedicarboxylate and 1-methylpyrrole com-... 

Methyl pyrrole-l-carboxylate and dimethyl acetylenedicarboxylate combine at 170°-200°C, giving trimethyl pyrrole-1,3,4-tricarboxylate (46) and acetylene. This reaction probably proceeds through the... 

Selective oxidation of methyl pyrroles 65 possessing an a-carboxylic ester and sensitive p-substituents can be accomplished using cerium triflate in methanol <96TL315>. Moreover, the resultant a-methoxymethylpyrroles 66 may be converted to dipyrrylmethanes 67 in a "one-pot" sequence by treatment with 48% HBr. The dipyrrylmethanes, in turn, can be further oxidized to dipyrryl ketones by ceric ammonium nitrate <96JHC221>. 

Metapone madagascarica M. new species W-PG Trail following Methyl pyrrole-2-carboxylate 140 [182]... 

Methyl 2-pyrrole carboxylate was transformed in two steps into an N-pyrrolylalanine derivative which was converted into a pyrrolo[l,2-a]pyr-azine after heating under reflux in toluene. Five subsequent steps led to peramine (Scheme 50), a principal insect feeding deterrent, from Acremo-nium iolli (88CC978). 

Table 2 Difference of chemical shifts (AS, ppm) a of 31a and 8a carbons relative to carbons of furan and methyl pyrrole-2-carboxylate...

Positive sign denotes a downfield shift from furan and methyl pyrrole-2-carboxylate, respectively. Chemical shifts for furan are 143.6 (C-2), 110.4 (C-3) <1975CS211>, and for methyl pyrrole-2-carboxylate 122.0 (C-2), 115.1 (C-3) <1974JP21004>. 

The benzene ring has been proposed as an isosteric replacement in a dipeptide to enforce either the tram l1 1 or the cis conformation 312>31 (Scheme 1). Similarly, 2-(amino-methyl)pyrrole-l-acetic acid (8, R = H) has been proposed as a cis peptide bond mimic,141 having the same number of atoms between the amino and carboxylic acid functions as in a dipeptide. Several other amino- and carboxy-substituted aromatic structures have been used as spacers in peptides 2-, 3-, and 4-aminobenzoic acids (Abz, e.g., 7), 2-, 3-, and 4-(amino-methyl)benzoic acids (Amb, e.g., 2), 2-, 3-, and 4-(aminophenyl)acetic acids (APha, e.g., 5), 2- (4), 3-, and 4-(aminomethylphenyl)acetic acid (Ampa), (aminomethyl)pyrrole-, -thiophene-, and -furancarboxylic acids 6, (aminomethyl)pyrrole- 8 and -thienylacetic acids, and aminobiphenylcarboxylic acids. 

Acheson and Vernon,75 and later Gabel,76 studied reactions of methyl pyrrole-1-carboxylates (12a) with DMAD. They obtained the pyrroles 14 and identified the acetylene formed, but were unable to isolate the proposed intermediates, azabicyclo[2,2, l]hepta-2,5-dienes (13). The... 

A more recent development has been the synthesis of bisamidopyrrolylmethane based anion receptor systems (Figure 19).15 These receptors might be regarded as containing half a calix[4]pyrrole combined with die 2-amido appendages in common with the pyrrolic amide cleft. Compounds 19 and 20 were synthesized by reaction of diethyl-5,5 -methylenebis(4-ethyl-3-methyl-2-pyrrole) carboxylate with aniline or n-butylamine in the presence of trimethylaluminium in dry dichloromethane at 35°C in 40 and 43% respective yields. 

Trail Pheromones. Tumlinson et al. (133) identified methyl 4-methyl pyrrole-2-carboxylate (XXXVT as the major trail pheromone of the ant, Atta texana. Another poison gland product, 3-butyl-5-methyloctahydroindolizine (XXXVI) has been reported to be the dominant releaser of trail following for workers of Monomorium pharaonls (134).In contrast to these cyclic releasers... 

Preparation of A,-methyl-4-[(A, -methyl-4-nitro-pyrrolyl-2-yl)carbonylamino]-pyrrole-carboxylic acid chloride... 

Heterocyclic compounds containing a nitrogen atom commonly undergo N-alkylation or C-alkylation. N-Methyl pyrrole can be prepared by interaction of methyl iodide with potassium pyrrole (40%). N-Carbethoxy pyrrole is made from chloroformic ester and potassium pyrrole. The C-alkylation of pyrroles has been discussed. 3-Alkylindoles are made by the alkylation and decarboxylation of indole-2-carboxylic acid. The conditions for alkylation of pyrrolidine are analogous to those employed for the alkylation of a secondary amine. Thus, pyrrolidine on treatment with n-butyl bromide and potassium hydroxide in boiling benzene is con-... 

When the lactam (41.1) is heated with acetic anhydride and DMAD, both methyl and carboxyl groups are lost during the formation of a fused pyrrole ring [3542]. Heating a side-chain ester (41.2) with soda-lime brings about annulation of the a-methylene group to the lactam carbonyl [2794],... 

Substituted indoles are of biological interest and are not readily synthesized by conventional methods of indole chemistry. Annulation of a nuclear methyl and an a-ethoxyimine (or an imidate) under basic conditions is a promising procedure. The pyridine oxide ester (87.1) may be converted in high yields into two kinds of pyrrole carboxylic ester the potassium salt of the imidate, on heating in DMF, gives the 3-(2-oxocarboxylate) whereas dilute mineral acid leads to the 2-carboxylate ester. 

The reaction of vinyldiazocarbene 17 parallels that observed with methoxybenzenes. Due to the ability of the nitrogen to stabilize a positive charge, only the alkylation product 168 is obtained. Methyl pyrrole-l-carboxylate, however, on reaction with 17 affords the tropane skeleton... 

Ludwig. This compound has an empirical formula corresponding to structure (1) and shows the ultraviolet and infrared" absorptions of a pyrrole-3-carboxylic ester. Its acetylation gives a tetra-O-acetyl derivative." Oxidation with lead tetraacetate yields ethyl 5-formyl-2-methyl-pyrrole-3-carboxylate (4), identical with the compound prepared in a different way. Oxidation with potassium permanganate in alkaline solution at low temperature yields 3-(ethoxycarbonyl)-2-methylpyrrole-5-carboxylic acid (7) which can be transformed " into the diethyl ester (8), identical... 

Ethyl 2-methyl-4-(D-ara6mo-tetrahydroxybutyl)pyrrole-3-carbothiolate (18) yields a tetra-O-acetyl derivative, and, on oxidation with periodic acid, affords ethyl 4-formyl-2-methylpyrrole-3-carbothiolate (22). Lactone (27) gives a tri-O-acetyl derivative and, on alkaline hydrolysis, consumes one equivalent of base and furnishes 2-methyl-4-(D-arofemo-tetrahydroxy-butyl)pyrrole-3-carboxylic acid (19) in almost quantitative yield. This acid can, in turn, be transformed into a tetra-O-acetyl derivative, and, when oxidized with sodium metaperiodate, it gives 4-formyl-2-methyl-pyrrole-3-carboxylic acid (23). Attempts to determine the size of the lactone ring in compound (27) by oxidation with sodium metaperiodate were unsuccessful three moles of metaperiodate were consumed per mole, as if, during the oxidation, hydrolysis of the lactone had occurred. 

Reversed-order addition is also applied in the alternative procedure for 1-methyl-pyrrole-2-carboxylic acid. In this way the chance of introduction of moisture is minimized. This method is generally applicable if the organometallic intermediate is... 

---