contemporary hbtory
LEONARD editedFINE by: Columbia University New York. NY 10027
ERIC S. PROSKAUER
of Heterocyclic Chemistry E. Campaigne Indiana University, Blwmington, IN 47405
A heterocyclic nucleus is a ring in which a t least one atom is not carbon. Compounds containing aromatic heterocyclic nuclei have been known since the earliest studies in organic chemistry. For example, Brugnatelli in 1818 ( I ) isolated alloxan (2) by oxidizing uric acid (1).
Other derivatives of uric acid (purines and pyrimidines) were described by Wohler and Liebig in a paper entitled "Uutersuchungen iiber die Natur der Harnsaure" in 1838 (2).In this interval, Dobereiner (3)isolated the furan derivative, furfural (3), by treating sugar or starch with sulfuric acid.
Much later, Perkin synthesized benzofuran (4) from coumarin ( 4 ) , but unfortunately he contributed to the heterocyclic confusion by naming his compound "coumarone". Benzofuran was found in coal tar in the 1890's. Pyrrole (5) was detected in the dry distillation of bones and other protein-containing materials in 1834 (5). The name was derived from "fiery oil", because i t colored a wood splint moistened with mineral acid fiery red. The pure oil was later analyzed and assigned the empirical formula C4H6Nby Anderson (6).
The discovery that indole (6), a henzpyrrole, was the nucleus of indigo, a commercially important dye, and that pyrrole was an important structural unit in hemin, bilirubin, and 860
Journal of Chemical Education
chlorophyll, occurred in the latter half of the 19th century. The first thiophene derivative, called "thiouessal" by its discoverer Laurent in 1844 (7) was tetraphenylthiophene. However, thiophene (7) itself was isolated by Victor Meyer in 1882 (8)after he discovered that pure benzene failed to give the indophenin test and that this test depended on the presence of traces of thiophene in benzene obtained from coal tar distillation.
Benzothiophene was originally called "Thionaphten" by its discoverers (9).but important advances in the chemistry of 8 occurred after 1906, when Friedlander synthesized the first thioindiao dve. thus recoanizina- the analoav -.between indole and beniothiophene (lo
