Syntheses of Carpyrinic Acid and of Related Pyridines with Long Aliphatik Chains

Four different syntheses of carpyrinic acid, i.e. 8-(5-hydroxy-6-methyl-2-pyridyl)octanoic acid, are reviewed in this paper and the synthetic value of individual steps is compared and discussed. The synthesis of another type of a long-chain pyridine derivative is presented, namely that of dehydroprosopine [5-hydroxy-2-(11-hydroxydodecyl)-6-hydroxymethylpyridine] which is a key intermediate in the total synthesis of the alkaloids prosopine and prosopinine. Finally, the syntheses of the ant venoms of related structures via the corresponding pyridines are reviewed. The long-chain pyridines are potential intermediates for a large group of piperidine derivatives of considerable and manyfold biological interest. 1. Syntheses of Carpyrinic Acid 1.1 Rapoport's Synthesis 1.2 Govindachari's Synthesis 1.3 Gruber's Synthesis 1.4 A Novel Synthesis 2. Synthesis of (±) 5-Hydroxy-2-(11-hydroxydodecyl)-6-hydroxymethylpyridine (Dehydroprosopine) 3. Synthesis of Ant Venoms (2-Methyl-6-alkyl- and -6-alkenyl-pyridines, their Derivatives and Homologs).