4-Methylpyrrole-2-carboxylate

The Barton-Zard pyrrole synthesis has now been extensively applied to synthesis of natural and unnatural products containing pyrrole units. Methyl 4-methylpyrrole-2-carboxylate is the trail-maker pheromone of the Texas leaf-cutting ant Atta texana.24 It is readily prepared by the Barton Zard method in 60% yield (Eq. 10.22).22... 

Acromyrmex ubterraneus subterraneus W-VG Trail following Methyl 4-methylpyrrole-2-carboxylate 64 [158]... 

Within Hymenoptera, pheromones produced by workers in social colonies are the best studied across many genera, principally in ants [6], with those eliciting trail following most extensively studied. The distinct behavior and the relative ease of the bioassay have resulted in chemical identifications in many species [ 113,114]. Those that have been recently identified are listed in Table 5. In addition, several alarm and recruitment signals have recently been identified. Many of the compounds recently identified in ants have previously been reported as trail or alarm pheromones in other ant species. For example, methyl 4-methylpyrrole-2-carboxylate 64, 3-ethyl-2,5-dimethylpyrazine 65, (9Z)-hexadec-9-enal 66,4-methylheptan-3-ol 67, and methyl 6-methylsalicy-late 68 have been identified as trail pheromone components, and heptan-2-one 69,4-methylheptan-3-one 70, formic acid 71, undecane 61,4-methylheptan-3-ol 67, methyl 6-methylsalicylate 68, and citronellal 72 have been identified as alarm pheromone components [6]. The use of the same chemicals across genera, with some used for very different functions, is an interesting phenomenon. 

Methyl 4-methylpyrrole-2-carboxylate, trail pheromone of the leaf-cutting ant... 

Methyl 4-methylpyrrole-2-carboxylate (Ar7) was the first trail pheromone identified in ants. It is used by Atta texana,231 Atta cephalotes232 and Acromyrmex octospinosus233 Two Metapone ant species use the unsubstituted derivative Ar40 as the trail pheromone.234 Methyl nicotinate (Ar41) is the minor component of the trail pheromone of an Aenictus sp.196... 

A trace constituent in the venoms of the myrmicines Atta texana, A. cephalotes, A. sexdens, and Acromyrmex octospinosus is methyl 4-methylpyrrole-2-carboxylate (X) ( 13, L4, lj[). This simple pyrrole... 

Similar conditions were used to prepare pyrroles from both t-butyl and benzyl isocyanoacetate. <94JHC255, 94S170> The reaction was also effective for preparing some rather hindered 3-aryl-4-methylpyrrole-2-carboxylates. Several p-methylnitrostyrenes were prepared by condensation of an aromatic aldehyde with nitroethane. These nitrostyrenes condensed with ethyl or methyl isocyanoacetate. Even o,o -disubstituted... 

Insect pheromones, which serve to convey messages between insects, have been isolated from many species and found to be both highly specific, and effective in mere traces. They are often aliphatic compounds, such as the termites trailfollowing substance, dodecatrien-l-ol, but that secreted by the town ant is methyl 4-methylpyrrole-2-carboxylate, and several ant and beetle pheromones are derivatives of pyrazine (Barlin, 1982). 

A mixture of startg. nitroethylene, ethyl isocyanoacetate, and DBU in tetrahydro-furan stirred at room temp, for 15 h ethyl 3-hexyl-4-methylpyrrole-2-carboxylate. Y 78%. F.e.s. N. Ono, K. Maruyama, Bull. Chem. Soc. Japan 61, 4470-2 (1988) review of pyrrole synthesis from aliphatic compds. s. L.N. Sobenina et al., Russ. Chem. Rev. 58, 163-80 (1989). 

Methylpyrrole-2-carboxylic acid (compound B) is the trail pheromone of the ant species Atta texana. A third of a milligram has been estimated to be sufficient to mark a path around Earth, and each ant carries only 3.3 ng (10 g). Propose a s3mthesis starting from 3-methylcyclobutene-1-carboxyUc acid (conqtound A). (Hint What dione is the retros3mthetic precursor to compound B, and how can you make it from compound A )... 

Methyl 4-methylpyrrole-2-carboxylate (Figure 9.16) is non-basic. It is the trail pheromone of some leaf-cutting ants. It is probably made from leucine by oxidation and cyclization. 

Methyl-3-heptanone (386a, Scheme 68), the alarm pheromone of the Texas leaf-cutting ant (Atta texana) was synthesized by Riley et al 173, 174) and required resolution of the intermediate, racemic 2-methyl-4-pentenoic acid (384). A convenient synthesis of methyl 4-methylpyrrole-2-carboxylate (392), the trail pheromone of A. texana, has been reported by Sonnet (775) (Scheme 69). Formylation of ester (390) with CUCHOMe and AICI3 gave predominantly the desired 4-formyl derivative (391). 

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